Hello,
Updating Avast led to an unbootable system. Windows Vista 64 Ultimate.
Cleaning avast off the system returned the system to a bootable state, but it is now unprotected.
Any ideas? Also filed as ticket: YNM-648536
Thanks.
PS Just having the ability to go back a version would be great until this issues is figured out.
Well if you ever get an answer post it here please.
I have the same issue and I too sent in a ticket on 06.03.2013 (FFD-850434 by the way).
The issue itself over 2 weeks now.
The best I have gotten from “support” is received as status.
I also have Windows Vista64. Not tech savvy, but I repost below how I was able to install Avast! 7 after trying to update to Avast! 8 and having big problems.
Update: I first ran CCleaner64 to clean up the mess in my registry. Then I noticed that Microsoft wanted to install an update and so I let it. I then ran the Avast! clean uninstall ap in safe mode. I then double clicked on the Avast! Pro install short cut on my desktop and the dialog box that opened said that my Avast! version needed updating and so I let it using my existing license. But lo and behold after the successful download and installation, it turns out that I re-installed version 7 not 8. Works fine now.
2nd update: Avast! has been sending me new virus definition files for my Avast! 7. So they must be aware of what has been happening.
I am also using Vista 64 Ultimate and have the same problem.
I updated using the option in maintenance, rebooted and it froze at the windows loading screen.
So far I tried uninstalling with aswClear and reinstalling manually and had no luck, I then uninstalled with aswClear and tried the 8.0.1483 update as suggested in this post and it made no difference.
I understand that the amount of Vista users is considerably lower than Windows 7 or XP so we might not be the highest priority for Avast staff at the moment but a stickied thread addressing the problem or at least a “we are working on it” type acknowledgement of the issue would be reassuring.
If you want to go back to version 7, here is the URL to it:
I have the same issue with the same OS. The Avast software was updated yesterday and I rebooted my machine tonight but it wasn’t working. The computer froze when it was showing “Microsoft Corporation”. I had to remove Avast in Safe mode to fix the issue.
Thanks for the link Kilia, I guess version 7.0.1474 link you provided will have to do for now.
Hopefully Vista 64 users will not be expected to use an outdated/inferior version for much longer.
Let’s keep our fingers crossed. 
I’m not tech savvy at all. Geezer. And I have the same issue as ‘blackvx’ except my pc is completely locked up. I can’t interrupt when I boot it up to even select ‘safe mode’.
The only problem I got, is BSOD. And that came the exactly same day I installed newest Avast on my Windows 7 64Bit OS.
I guess I need to uninstall newest Avast to get rid of the BSOD that I get everytime I restart or start my computer.
I had the same issue with Windows XP and the upgrade. I’m posting a separate topic, but no resolution yet.