Jan11Written by:Rod Weir
Friday, January 11, 2008 12:00 AM
What to do when your Vista machine's CPU runs at 100%
Time for a helpdesk techo blog.
Ever since upgrading to Vista, one of my machines has been plagued with the CPU running at 100% whenever I open a network folder or mapped drive. Anytime I do this, the file folders in Explorer have a little revolving/spinning magnifying glass that will stay there until I reset the machine. A quick review of the Windows Task Manager reveals that explorer.exe is the culprit, and it will stay at or close to 100%, making the machine virtually useless.
It seems I'm not the only person having this issue. A quick google search on terms like "vista cpu 100%", "vista explorer.exe cpu 100%" or similar displays a huge amount of people having the problem. At least I'm not the only one - however solutions seem to be scarce and random at best. After searching through a lot of newsgroups, webpages, blogs and other corners of the internet to try and fix the issue, I've come up with a partial solution to recover control over an over-zealous explorer.exe.
Use this method at your own risk.
Download and install Process Explorer from Microsoft. This product can best be described as the Windows Task Explorer on steriods. It tells you everything your system is doing, right down the each processor thread and file that is being used. Process Explorer was originally developed by SysInternals - a company that was later acquired by Microsoft.
http://technet.microsoft.com/en-gb/sysinternals/bb896653.aspx When your CPU starts maxing out at 100%, fire up Process Explorer and have a look at what's happening under the hood. As expected, it's explorer.exe that consuming 100%. Process Explorer allows you to dig deeper into this application. Double-click explorer.exe to have a look at all the threads it uses.  Sort by "CSwitchDelta" and have a look at the top thread. On my particular machine, it's a process with a "Start address" named "ntdll.dll!Rt|IntegerToUnicodeString+0x67" that is always CPU intensive thread.
I'm not exactly sure what this thread does (anyone?), but killing it restores the CPU back to a normal level immediately.
Sometimes I get an error message a few minutes later saying "Explorer has stopped working", and after click OK, it re-starts and the machine is OK.
While I realise this isn't the most elegant way of addressing this issue, perhaps this information might give someone with a bit more knowledge about Windows processes some ideas as to why this is occuring in the first place. There must a few helpdesk technicians out there who have run into this issue. If anyone else has some insight into the famous "Vista CPU 100%" problem, please share!
Hasta la Vista.
Rod 13 comment(s) so far... Re: Vista explorer.exe CPU 100% problem
Exactly the same issue here. It started occurring on Vista Business after installing KB929547, at about the same time I started using an external USB HDD, and this issue--high utilization--is making my system completely unusable.
By Kirk M. Schafer on
Thursday, January 24, 2008 3:28 AM | Re: Vista explorer.exe CPU 100% problem
Kirk, thanks for your post. I've checked my system and it doesn't have KB929547, so that can't be the issue...at least on my machine. I also have USB devices (mouse + phone) so I'll do some checking on these also to see if USB is the real problem here.So far I've tried turning off disk indexing, Readyboost, SuperFetch and a whole stack of other system processes, but nothing seems to fix this issue.I'll keep working on it.Rod
By Rod on
Saturday, May 15, 2010 10:45 AM | Re: Vista explorer.exe CPU 100% problem
Breakthrough!I discovered that we had a 1Gb zipped file sitting in the root folder of one of our network mapped drives. This zip archive had hundreds of sub-folders within it. Whenever Windows Explorer was opened to this location, it spent all of it's time trying to look inside this zip file (indexing / virus check?). Even when I closed Explorer, there was an explorer.exe process that continued to interogate this file and causing the CPU to max out. I checked this behaviour on another machine and the same thing was occurring.I moved this file to another location and the problem seems to have gone. In order to do this however, I needed to restart the machine, because the file was constantly in use.Once again, they SysInternals tools came to the rescue. This time I used Process Monitor to examine what the machine was doing at the file / registry level. You can download Process Monitor from here.http://technet.microsoft.com/en-gb/sysinternals/bb896645.aspxHope this helps someone out there.Best regards,Rod
By Rod on
Saturday, May 15, 2010 10:47 AM | Re: Vista explorer.exe CPU 100% problem
Rod, Thanks for the pointer to "ntdll.dll!Rt|IntegerToUnicodeString+0x67". This is part of the problem but not all of it.
The other large files created by Vista on Root drive are hiberfil.sys and pagefile.sys (near 4Gig each on mine) Currently looking into those.
MS Outlook seems to be unhappy on Vista accross most of the users of Vista I know and the CPU issue seems to compound when Outlook is running for me.
Loved the SysInernals tools - thanks.
Best regs
Guy
By guy.thornycroft on
Wednesday, February 06, 2008 11:55 AM | Re: Vista explorer.exe CPU 100% problem
Hi Guy,
I'm glad this information was helpful. From what I can tell, as soon as the Vista explorer sees a large file (be it a zip file, video, movie, pagefile etc), it spends an awful lot of time and processor power trying to dig into that file for some reason.
Regarding Outlook exacerbating the problem, perhaps it's because your .pst files, are quite large - maybe containing a lot of email attachments etc. Have you tried archiving your mailbox - maybe even moving it to a different drive?
I'm hoping the Vista service pack coming soon will correct this issue, but I'm not holding my breath.
Happy to hear you liked the SysInternals tools - spread the word!
Best regards,
Rod
By Rod on
Thursday, February 07, 2008 8:21 AM | Re: Vista explorer.exe CPU 100% problem
Hellllllppp!!
Same problem here... when I kill the thread, explorer.exe crashes almost immediately. "Suspend" to work however. I could not find any new large files that could be causing this. Also, if it's the indexer that's causing this problem, wouldn't disabling the Search Indexer service solve this?
Thanks for you tips!
-Gino
By Gino M. on
Wednesday, February 27, 2008 8:08 PM | Re: Vista explorer.exe CPU 100% problem
Hi Gino,Did you try using ProcMon from SysInternals to see what file explorer.exe is stuck on? If explorer.exe is using a lot of CPU, then it's trying to access something. ProcMon will tell you what it is.In my case, it wasn't the indexing service causing this. It was the big file in the root directory of a mapped drive.Do you have a USB device plugged in that contains large files? If so, try unplugging the USB device and see if the problem goes away.Rod.
By Rod on
Saturday, May 15, 2010 10:46 AM | Re: Vista explorer.exe CPU 100% problem
Just when I started to get a little more comfortable with vista - doing some decent video edit/importing, explorer.exe maxes out my cpu 100%, just the same as others above have said. I am looking through ideas, trying them all, one by one of course but I also remember a similar problem with xp, opening up any folder containing a slightly corrupt .avi / .MOV and/ or jpeg.
before the problem arose I had earlier been trying to recover some deleted files from a friends pc using 'Photorec'. The programme was good in that it did recover some very important information for a friend (from his hard drive taken out of his machine) but not everything was recoverable from the drive - something to do with 'sectors' having already been overwritten by the time the mistake had been notice, and his machine died!
Anyway the result was that corrupted files were also displayed in the Photorec created directory, (on my pc) as thumbnails, and explorer.exe maxed out in a similar fashion. My cure was to tease them apart, the good from the bad, (create a folder for each) as quick as possible before explorer.exe went mental again. Sorry if that's not pc but I think I went the same way in dealing with the problem!!! It also helped when thumbnails were disabled and list view was used instead. I DO NOT KNOW WHY - IT JUST DID. Anyway, although what I am saying may not be useful here, since I am looking for cure too, I guess it cannot hurt anyone to share a little insight of similar problems. Sharing makes all the difference to life's little problems.
Praying for a cure to all these ills.
Vince
By Whocareswins on
Sunday, November 16, 2008 3:05 AM | Re: Vista explorer.exe CPU 100% problem
I got the same problem on my notebook running Vista, whenever clicking on the C drive.
My problem was solved after I disabled indexing the drive (right click on the drive, choose 'Property', uncheck the 'Indexing' box under the 'General' tap, apply the change to all sub-directories).
Worth a try.
By Nobody on
Sunday, February 22, 2009 6:23 AM | Re: Vista explorer.exe CPU 100% problem
I've got the same problem.. and after hours searching the solution over the internet, I finally got It!!
Just create a new User profile and the problem's solved!!
By Chris on
Friday, March 27, 2009 3:41 PM | Re: Vista explorer.exe CPU 100% problem
I had the exact same problem. You have well documented. Just while looking at your writing. I clicked on Desktop on Windows Explorer under Folders on my Vista x64. When Drives were showing, 100% CPU. When drives were hidden, 4%. So it was definiately one of the drives that was causing it. I removed my USB 1 media hub for my SD and CF card. Viola, CPU usage went down to 4%. Something happened. My Windows were trying to do something or looking for something in my removeable drive. Buggy ass windows.
By Jonathan Kim on
Monday, September 21, 2009 5:47 PM | Re: Vista explorer.exe CPU 100% problem
OK, so it's been a while since I wrote this. Now that Windows 7 is out, is anyone still having this issue?
By Rod on
Friday, November 20, 2009 7:48 PM | Re: Vista explorer.exe CPU 100% problem
thanks bro for your help. this seems to solve my problems.
By Anvesh on
Tuesday, December 01, 2009 3:16 AM |
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