Hi all. Is there an answer for “yes, classic case of such and such” why my PC crashes every time !avast starts a system scan? This also happens with any spyware scan, ie: Ad-aware/Spybot and M$ new one. Just wondering if there is a common, well known thing to check before I get down to the nuts and bolts. TX! 
Since the crash happens with multiple applications, it is very likely a damaged OS.
I suggest you backup the data and do a clean install.
or:
Try HijackThis to see if there is malware on your system causing this.
What operating system are you using?
What does it mean “crash”, exactly? A blue screen?
Thanks
Vlk
I don’t understand this “bluescreen” I see mentioned all over. I have never had a “bluescreen crash”. I have had spontaneous reboots but what happens here is my PC just FREEZES. I can’t move the mouse or toggle to anything. I have to manually reboot the PC with the power button. No blue screen, just what was on the monitor is frozen.
Ok, I will do a XP Repair.
I’m running XP Home.
Logfile of HijackThis v1.98.2
Scan saved at 10:00:33 AM, on 2/15/2005
Platform: Windows XP SP1 (WinNT 5.01.2600)
MSIE: Internet Explorer v6.00 SP1 (6.00.2800.1106)
Running processes:
C:\WINDOWS\System32\smss.exe
C:\WINDOWS\system32\winlogon.exe
C:\WINDOWS\system32\services.exe
C:\WINDOWS\system32\lsass.exe
C:\WINDOWS\system32\svchost.exe
C:\WINDOWS\System32\svchost.exe
C:\WINDOWS\system32\spoolsv.exe
C:\Program Files\Alwil Software\Avast4\aswUpdSv.exe
C:\Program Files\Alwil Software\Avast4\ashServ.exe
C:\WINDOWS\System32\NMSSvc.exe
C:\WINDOWS\System32\svchost.exe
C:\WINDOWS\Explorer.EXE
C:\Program Files\Alwil Software\Avast4\ashMaiSv.exe
C:\Program Files\Analog Devices\SoundMAX\Smtray.exe
C:\WINDOWS\system32\dla\tfswctrl.exe
C:\Program Files\Java\j2re1.4.2_06\bin\jusched.exe
C:\Program Files\NetLimiter\NetLimiter.exe
C:\PROGRA~1\ALWILS~1\Avast4\ashDisp.exe
C:\Program Files\Mozilla Thunderbird\thunderbird.exe
C:\Program Files\Mozilla Firefox\firefox.exe
C:\WINDOWS\System32\SNDVOL32.EXE
C:\HijackThis\HijackThis.exe
R0 - HKCU\Software\Microsoft\Internet Explorer\Main,Start Page = http://www.cnn.com/
R0 - HKLM\Software\Microsoft\Internet Explorer\Main,Start Page = http://www.cnn.com
O2 - BHO: AcroIEHlprObj Class - {06849E9F-C8D7-4D59-B87D-784B7D6BE0B3} - C:\Program Files\Adobe\Acrobat 7.0\ActiveX\AcroIEHelper.dll
O2 - BHO: Google Toolbar Helper - {AA58ED58-01DD-4d91-8333-CF10577473F7} - c:\program files\google\googletoolbar2.dll
O3 - Toolbar: &Radio - {8E718888-423F-11D2-876E-00A0C9082467} - C:\WINDOWS\System32\msdxm.ocx
Is your computer overheating? Have you cleaned the dust out of the systems unit recently? Do your fans make alot of noise?
It’s clean. But I think there’s an important point being forgotten. It ONLY happens when I run an !avast scan or a spyware scan. Something to do with deep scans that freezes my PC… I thought there might be an obvious thing to look into or at least see other posts about this but, I guess it’s a pretty unique probby. LOL
Seems like a problem relating to your hard drive or data corruption.
When windows crashes it automatically reboots, there is a way to disable this so that instead you get a blue screen with information about what caused the crash.
To do this
right click my computer
properties > advanced
Go to “Startup and recovery”
and click on settings.
Look for “System failure”
and untick “Automatically restart”
Now run something that caused your pc to restart.
Should you get a blue screen write down what caused the system to crash and post it here.
I also think you should backup your files on another hd or cd media before trying what i am about to say below.
Can you run a defrag and see what happens.
And last of all
Open an ms- dos prompt screen
and type chkdsk
What does it say?
C:\Documents and Settings\PPM>chkdsk
The type of the file system is NTFS.
Volume label is IBM_PRELOAD.
WARNING! F parameter not specified.
Running CHKDSK in read-only mode.
CHKDSK is verifying files (stage 1 of 3)…
File verification completed.
CHKDSK is verifying indexes (stage 2 of 3)…
Index verification completed.
CHKDSK is recovering lost files.
CHKDSK is verifying security descriptors (stage 3 of 3)…
Security descriptor verification completed.
CHKDSK discovered free space marked as allocated in the
master file table (MFT) bitmap.
Correcting errors in the Volume Bitmap.
Windows found problems with the file system.
Run CHKDSK with the /F (fix) option to correct these.
37849108 KB total disk space.
15962728 KB in 48121 files.
14328 KB in 3367 indexes.
0 KB in bad sectors.
147076 KB in use by the system.
65536 KB occupied by the log file.
21724976 KB available on disk.
4096 bytes in each allocation unit.
9462277 total allocation units on disk.
5431244 allocation units available on disk.
Hmmmm… volume is busy, hold up. Doing a chkdsk /F
Okay, I unticked “Automatically restart” and ran an !avast scan. Once again, my PC just froze, NO bluescreen.
Cursor is locked on !avast screen and I can’t do anything except reboot with the power button.
Really looks more and more like an XP Repair is in order… gonna have to get a CD because the Recovery Disks wipe everything.
If it weren’t a problem for you to transfer big files, you could follow Vlk’s description and create a memory dump (using keyboard-invoked bluescreen) - when the computer is frozen.
I guess Vlk might be interested to take a look at the dump 
Have you done anything to your PC recently?
Like add new hardware / memory?
Okay, I just did the Registry add-on and now I’m running an !avast scan waiting for the freeze.
No, no new memory or hardware. Better go before the freeze!
Okay, I couldn’t create a Bluescreen, just the freeze.
Also, there is no "\Windows\memory.dmp
The closet thing I can see is a Minidump Folder with a 64KB file. Not the right thing eh?
Well, here is that minidump:
I’m afraid the minidump won’t be enough.
Did you reboot after you added the registry key? Also, make sure you don’t add a trailing space character after the value name, for example.
I found something, but I can’t find MEMORY.DMP
Yes, I rebooted after the Reg entry, see pic.
I changed the memory dump path. I still can’t find it after recreating the freeze and holding CTRL and clicking twice on Scroll Lock. heh…
So, no bluescreen appears when you use the special shortcut? (Also, you used the right Ctrl key, right?)
What keyboard do you have? (USB maybe?)