Hi, I am setting up a new Win7 64 PC and avast! installed fine and updated correctly. However, when I try to update now, it fails withthe invalid file signature message. Any suggestions please?
Hi
for me the same: my AIS 5.1.889 @ Win7-64bit comes back with the “Update fails: invalid file signature” when it tries to update to 110117-0. All updates before that went fine.
Funny: my WinXp-32bit updated correctly.
Could it be a 64bit thing?
Thanks for your support.
Yes, a clean instal results with the same error. I really thought the bugs were gone. 
Same thing. Red square - cannot update. invalid file signature
Oh well. I will have to use Windows Security Essentials for now.
Same error here
AIS 5.1.889 Win7-X64
No problems for me and I use a 32bit system.
avast! just updated automatically this morning and the current definitions are 110117-0.
Anyone (except who already posted) with 64bit system is having the same problem?
Now whats up with invalid file signature(auto updates)!!!
Lets get this corrected please :
One minute you have to uninstall every part of avast to get the new version to work
next it wouldn’t update even with permanent connection to internet ticked had to be now use internet explorer settings
Now it won’t update as its invalid file signature(win 7 64 bit), whats next?? ;D
Your older versions worked good for eons ;D
Same problem Win7 64bit
just happen today
Sadly, this once great program is getting very unreliable. I cannot complain though as it is provided free.
Please be patient, it should be fixed soon.
Vista Bus 64
Program 5.1.889
Virus Def version 110113-0
Same here too, Invalid file signature. Setup will terminate
This started “several days ago” (if I could be more specific, I would) but it was at or about the time Avast Updater installed the update program as part of auto updates. I only today uninstalled Avast, reinstalled, tried to updated and Googled the error did I come across this forum and thread
??? 
Unreliable? I’ve been using Avast for years and it has yet to either fail or disappoint me. As a matter of fact, the problem with this update is -as far as I can remember- the first I’ve ever seen.
So for those having problems updating - don’t worry, don’t dispair, don’t go mad. Avast! will fix the definition file soon.
– Update: as a matter of fact, it has been fixed now! I just manually updated succesfully.
I am having the same problem on win7 64-bit.
Appears to be corrected
Mine just did an auto-update without any problems
Its updated now okay in maintenance section when I clicked on the button in there
No more invalid file signature thinghy
I run the following (dualboot and virtuel PC’s):
Windows 7 Ultimate (x64) → issue
Windows 7 Pro (x64) → issue
Windows 7 Enterprise (x86) → works
Windows Vista Business (x64) —> issue
Windows Vista Business (x86) → works
Windows XP Pro (x86) → works
All systems run Avast! Internet Security 5.1.889 (licensed for 10 PC’s for 3 years).
I am a little annoyed…
Btw as I recall the issue started on my x86 systems but after they ran again as they should, the x64 systems began having this update-issue after Saturday 15th of January 2011.
Oke then right after this post I did an update. It worked.
I am getting this too - Windows 7; 64 bit. I’m new to this program. I was hoping this would run smoothly. Do I do anything or does Avast take care of it?
Dear Avast, Virus definitions will not allow me to update this morning, Jan. 17th. I tried restarting my computers and ran a total virus scans, but nothing. Hope you fix the problem soon. Have to be extra careful visiting webstites now.
It’s already fixed…
Try to update your virus definitions now…