Solved explorer.exe uses full core pemanently, ntdll.dll!RtlValidateHeap+0x17

[geverl]

As soon as I open Windows Explorer, it uses a full core of my 4 core system. I'm running Windows 7 Pro 64 Bit. Process Hacker shows ntdll.dll!RtlValidateHeap+0x170 as start address for the thread that uses the processor resources. I've tried Process Monitor to find out what this thread is doing, but only the thread exit with success (after I've terminated it in Process Hacker) shows up in Process Monitor. A System Restore has brought no change. I can't find anything suspicious in Event Viewer.

How can I find out what causes this explorer.exe behaviour and resolve it?

 

[Layback Bear]

That happening normally means a infection.
Take a read here.

Igfxupdate.exe forces cpu to load @ 100% - Microsoft Community

I would recommend going the forum Security section.

 

[geverl]

I've run a full scan with both Microsoft Security Essentials and Anti-Malware. If these two cannot find the culprit, what else can I do?

 

[Layback Bear]

Well I still think you can be infected. That is why I recommended our Security section.

System Security - Windows 7 Help Forums

It would also be helpful if you filled in your system specs completely.
Including all all security programs you use normally.

Their are many things that can cause such a problem. The gambit is large.
We must know for sure your system is clean.
Then if need be their are other things that can be done.

 

[geverl]

I posted a reply here on Sunday, but somehow it seems to have been lost...
I've tried most of the software at http://www.bleepingcomputer.com/download/windows/security to no avail.
When I boot in safe mode with pretty much everything disabled, Windows Explorer works fine. After having wasted several days with useless scanner software I've installed an SSD drive and installed Windows 7 on it, which works fine. The disk on which the infected Windows 7 is installed is now used purely for data storage, although I can still boot into the infected Windows if need be.

 

[Layback Bear]

Why didn't you post in our Security Section as I recommended twice?