Explorer.exe uses too much CPU cycles (roughly 50%)... How can I fix this?

Question

Hi everyone,
In the last two days I have noticed a serious loss in system performance.  The first thing I do when I come accross a performance issue is to make sure that I don't have any scheduled automatic scans running in the background, such as my antivirus.  If they aren't, I then open the task manager and check to see what process(es) is(are) causing the performance issue based on CPU usage.  I discovered that explorer.exe is now regularly using approximately 50% of my CPU power AT ALL TIMES (with fluctuations ranging from as low as 35% to as high as 99%, but 45%-55% is the most common range).
Now I thought this might have been some sort of fluke, so I rebooted several times, and in all cases I find explorer.exe continues to use this hefty amount of CPU power.  This persists even if I leave the system alone (running, but not being used) for 15 minutes or more.
This is causing major performance issues with trying to run any/all other applications on the system, and even worse performance issues if I try to use explorer for something such as directory navigation, file searching, or file access.
I recently made an update to Windows (about a day before this problem arose), so I thought that might be the cause of this, so I ran a system restore to the restore point made before the install.  That didn't fix the problem.  Since the problem has only started in the last two days, I restored to a point three days ago.  That didn't fix it either.  I have since tried to restore to points 5 and 7 days old, and neither of those worked to fix this problem either.
I can use the task manager to end-task explorer.exe, and then restart it using "new task" from the file menu, and this seems to correct the problem.  After doing such a "restart" of explorer.exe, the process no longer uses 50% of my CPU power, and instead uses only 0%-20% depending on what I'm doing.  This, however, is not a viable long-term solution for a couple of reasons:  1) it screws up my tray icons, causing many to disappear even though their parent programs/processes are still running, and causing others to appear even though they shouldn't be there; and 2) subsequent instances of explorer.exe such as for directory navigation still have some performance problems and are prone to crashes.
I need to know how to repair or replace explorer.exe without having to format my hard drive and re-install (either from scratch or using a system recovery disc).  I can try using some sort of shell replacement such as Aston, Emerge, or GeoShell, but I shouldn't have to do that.
It may be that one of my other startup applications is causing some sort of compatibility issue, but that seems unlikely since I haven't made any changes to the system, nor installed any new software other than standard windows updates.
I need help, advice, suggestions, etc., or really anything at all that I can try that might fix this problem.  In the meantime, I am going to boot into safe mode to see if explorer.exe has problems even then (which would solidly indicate a corruption of explorer.exe rather than a compatibility issue or anything else).
Please help if you can.  For reference, I am using an HP Pavilion dv9700 CTO Entertainment Notebook PC, running Windows Vista Home Premium 32-bit with Service Pack 1.  I have an Intel Core2 Duo T9300 2.5GHz CPU and 3GB of RAM.  My explorer.exe file gives the following information from the Details tab of its Properties window:  file version is 6.0.6001.18000; product version is 6.0.6000.16386; file size is 2.79MB; and modification date is 1/20/2008 at 6:24pm.  As far as I know, that is all correct information and does not indicate that the program file has been replaced by any sort of malicious software.  I also ran a complete scan with AVG Antivirus and found no viruses or other malicious software anywhere on the system (unless you count tracking cookies).
Thank you in advance for any help

Answer 1

 Edward Lin wrote:
I have exactly the same problem!!!  And I concluded that the “AUTO CONNECT” function is the main reason of causing the CPU usage.  If I uncheck the “AUTO CONNECT” from the saved wi-fi connection, then the CPU would remain claim.
But.. Still, it’s very annoying.  So I formatted the hard drive and restore to the original factory condition.  Initially, it was working ok.  But after WINDOW UPDATES, the same problem happens again!!!!!!  May this be the bug from Microsoft??
Any thought??  Any Fix?  Please help!!!! 
Yes, I did notice that the problem started after I did a Windows Update.  I can't remember which update it was, but the strange thing about it was that I couldn't fix the problem by restoring the system to a restore point that was made BEFORE the update.  Since I hadn't made any other changes to the system between when it worked and when it stopped working, I can only assume that the update caused the problem, and as such I believe it IS Microsoft's fault.
As to the Auto-Connect feature, I hadn't even thought of that, but since I use my internet ALL THE TIME, it would be really annoying to have to manually connect every boot up.
Which brings me back to the workaround.  If you have Auto-Connect enabled, and you disable WLAN AutoConfig and set it to Manual in your Services interface, then reboot the system, does it solve the CPU issues?  If the answer is yes, then you can do what I'm doing:
1.  Go to Start, then in the search box type "task" and you should see the Task Scheduler come up as an option.
2.  Open the Task Scheduler and click on "Create Task..." (by default this should be on the right-hand side of the window in the Actions pane).
3.  In the General tab, give the task a name and (optionally) a description, and put a check mark in the box at the lower left that says "Run with highest privileges".
4.  In the Triggers tab, add a trigger.  In the new window, choose "At log on" from the dropdown box at the top, set it to run for "Any user", and then head to the advanced settings section of the window.  Put a check mark in the box for "Delay task for:" and set the delay for one minute.  Make sure that there is a check mark in the box for "Enabled".  Then click OK.
5.  In the Actions tab, add an action.  In the new window, make sure that "Start a program" is selected in the drop down box at the top (should be the default choice).  In the field where you specify the program to run, type in "SC".  In the "Add arguments (optional):" field, type in "Start wlansvc".  Then click OK.
6.  Go through the other tabs to make sure you're happy with all of the other settings.  The default values should be just fine, but feel free to change them if you want to.  Then click OK.
7.  Make sure that WLAN AutoConfig is still set to Manual.
8.  Re-enable your Auto-Connect feature.
9.  Reboot the system.
About 60 seconds after you log into your user account you should see a black command window flash onto the screen and then disappear again.  That is your automatic task running and starting up the WLAN AutoConfig servicve.  Another 30-60 seconds later and you should have access to your wireless network and the internet, and you don't have to interact with it or manually start anything.  You can also try setting the task delay to 30 seconds rather than 1 minute, but on my system that wasn't a long enough delay to prevent the CPU usage issues, whereas 1 minute was sufficient.  On my system, it enables the wireless before the system even finishes loading up my normal startup applications like my antivirus, so Idon't even notice a slowdown on the bootup process, let alone any wait time before I can use my internet.
This isn't a fix, and what we really need is for Microsoft to figure out what they did wrong, and fix it, but in the meantime, this works.
Good luck
On a side note:  Unless Microsoft gets busy on fixing Vista so that it's backwards compatible with my old games, I'm still going to downgrade to XP (like a LOT of people have been doing for various reasons)... assuming I can find XP compatible hardware drivers anyway.  Right now I can get more of my games to run under Linux than I can under Vista, despite the fact that they were programmed to run in a DirectX Windows environment only... that's simply unacceptable.