Avast causing BSOD

Avast Free Antivirus / Premium Security
1

I was having some issues with my last antivirus (MSE) so I changed to avast. After installing and running the analysis I started getting very frequent BSOD’s, particularly during start-up or after the laptop has been hibernating. I had run CCleaner after deleting the viruses so at first I thought I had deleted something I shouldn’t, but today I downloaded BlueScreenView and this is the dump file (this has happened 10-15 times, but for some reason there’s only one dump file):

==================================================
Dump File : 012014-124785-01.dmp
Crash Time : 20-01-2014 21:05:44
Bug Check String : KERNEL_MODE_EXCEPTION_NOT_HANDLED
Bug Check Code : 0x1000008e
Parameter 1 : 0xc0000005
Parameter 2 : 0xe3a85d72
Parameter 3 : 0xec467c7c
Parameter 4 : 0x00000000
Caused By Driver : aswSnx.sys
Caused By Address : aswSnx.sys+72a50
File Description : avast! Virtualization Driver
Product Name : avast! Antivirus
Company : AVAST Software
File Version : 9.0.2011.263
Processor : 32-bit
Crash Address : ntkrnlpa.exe+236d72
Stack Address 1 : aswSnx.sys+1ada9
Stack Address 2 : ntkrnlpa.exe+3d8c6
Stack Address 3 :
Computer Name :
Full Path : C:\windows\Minidump\012014-124785-01.dmp
Processors Count : 4
Major Version : 15
Minor Version : 7601
Dump File Size : 160.656
Dump File Time : 20-01-2014 21:08:49

After BSOD I only get a message saying Windows has shut down unexpectedly or something like that and asks if I want to find a solution, which doesn’t work. Avast seems to be working fine (updating, etc.). Any help, please?

I’m running Windows 7 32-bit on a Samsung R580 laptop.

My english is not the best so I’m sorry if something is unclear, just ask if you don’t understand anything (or if you need more information).

2

hi daniela_fg,

How many antivirus programs do you now have running on your system now? Running Win 7 or 8 or 8.1?

See: http://www.avast.com/faq.php?article=AVKB11#artTitle

Also see: http://antivirus.about.com/b/2007/03/11/clean-quarantine-or-delete.htm

3

Hi! Thanks for the reply.

I uninstalled MSE when I changed to avast, so I’m only running this antivirus. But now that you mention it, I’m also using a safety app called Trusteer Rapport, which protects bank account data and that kind of stuff:
http://www.trusteer.com/es/support/about-rapport (the link may open in spanish, just click the flag to the right :slight_smile: ). }
I don’t know how or if this could conflict with avast, just thought I should mention it.

I’m running Windows 7, 32-bit.

I checked both links above, thanks. So, could this be caused by some deleted file? Avast found like a million infected files during the first analysis (MSE wasn’t detecting them for some reason). I clicked the autimatic solution button so I’m not sure what avast did with them.

Thanks for the help :slight_smile:

4

In order for an active antivirus program to detect malicious files, it must upload many, many virus definitions into system memory or RAM. It is this ability, that of loading virus definitions in memory, that enables an antivirus program to provide real-time antivirus protection for your system.

So, what happens when an user runs two active real-time antivirus programs at the same time?

You get two 5,000 pound gorillas sitting on your system, ready to wreck havoc and inspect or destroy everything they can reach, which practically speaking, is everywhere, as an antivirus program is designed to run at the lowest and deepest levels of your system as well as at the highest level. Every time your system runs a new file, or uses program code to run a program such as Word, your a/v should, and does, look at these files at the moment they run and compares them to known malicious definitions.

Since the virus definitions in memory are made to be similar to actual malware that it can detect, so it is with the second a/v. The second a/v will see the others’ definitions and alert and say you have an infected file(s).

Since these are virus definitions, they are not malicious, and cannot infect your system. But the second a/v thinks they are, since they should not be there if running only one active a/v, but that is not the case here. Detections found under this two a/v scenario are always false-positive if related to definitions in the other a/v.

Worst case of two a/v’s clashing is when they both attempt to scan the exact same file in memory or on the hard drive at the same exact instant.

Your system freezes (halts) and a system crash ensues. Otherwise known as a BSOD. Your processor cannot give one or the other priority, as both each demand to get at the same file at exactly the same time.

I understand you’ve uninstalled MSE, but did you use the Microsoft tool to completely uninstall it?

Since you have experienced several BSOD’s, it is always a good idea to run a system file check, known as sfc.

Run this command in Win 7: sfc /scannow in a cmd prompt window. See attached pictures below on how to do that.

  • You’ll need to enter ‘cmd’ (without the quotes) in the menu box Search programs and files by clicking the Windows Start Button.
  • Next, go to the top and right-click cmd.exe and select run as administrator. If the UAC window pops up, allow.
  • cmd window will open.
  • Next, type in sfc /scannow Note the space between sfc and /scannow. Press enter and allow the program to finish and complete.
  • Do not interrupt or terminate this program for any reason whilst it is running, or use the system for any other purpose until it is finished.

Use your administrator account only for this operation.

Report back what sfc found in your next reply. If you are missing a needed and necessary system file because of the BSOD, sfc may fix that for you. It should complete in less than 1/2 hour, but YMMV depending on system speed and specs.