Can't open Avast 4.8 Home Edition

After I installed the Avast 4.8 Home Edition, I just can’t open the program as a pop up windows says “D/Program Files/Alwil Software/Avast4/ashAvast.exe is not a valid Win32 application”. What should I do now. Thanks.

Clean your system as it looks like it was infected before installing avast. The reason I say this is that this message is commonly seen when a system is infected by something like Beagle which has a rootkit to protect it.
Were you experiencing any suspect symptons befor e installing avast ?

Have (or did) you another AV installed in this system, if so what was it and how did you get rid of it ?

Also see, anti-rootkit, detection, removal & protection http://www.antirootkit.com/software/index.htm. Try these as they are some of the more efficient and user friendly anti-rootkit tools.

Run these one at a time and report any findings before moving on to the next.

You may need to reinstall avast if any of these finds any rootkit.

If those programs don’t do it, you could try Malware Bytes Anti Malware and SUPERAntispyware.

This sound like SmitFraud to me as I have seen this exact error with WinFixer and WinHound.

Virus moved and the Avast resumes normal now. Thanks.

You’re welcome.

What was it that was found (file name, location and malware name) and what program found it ?

I suggest you repair your installation:
Go to Control Panel > Add/Remove programs > avast! antivirus > Remove. Then choose Repair function in the popup window (Repair).

Hi!
I have the same problem. I’ve tried all the above but nothing works. They show same error ‘is not a valid win32 application’.
My pc is getting quite slow and dont know what to do. I use Spybot and is not working either. Dont know what else to do…
Please, can anybody help me???

neosito
You could try running them (try MBAM) in safe mode, and if that doesn’t work, try renaming the MBAM .exe to something like “gogetem.exe”, or anything you choose, really, and see if it will then run. If it does, update it and scan with it.

Some viruses/malware could destroy/mess the avast installation.
Use other tools to scan and get clean (like MBAM, Superantispyware) or full computer on-line scanning:
Kaspersky (very good detection rates)
ESET NOD32
Trendmicro housecall
F-Secure
BitDefender (free removal of the malware)