Vista fails to boot after avast update

[kirsti]

I currently use avast 4.8.1290 - professional edition and I'm running Vista Ultimate 64bits. The 21. Nov. avast wanted me to upgrade to the newest version. I clicked on the "new version available"-message and seemingly the installation went well. But when I rebooted Vista was not able to start properly. I had to run system restore to a point before the installation to fix the problem.

Today, avast want me to upgrade again. My colleague was faster than me and he upgraded first. He has an almost identical PC as mine and of course he encountered the same problem. Vista refused to start and in this case normal system restore wouldn't work. However, by choosing a system restore point made the 21. of Nov. he was finally able to start his computer.

Has anybody else experienced this problem or found a solution?

[DavidR]

Try a clean reinstall.

It would probably be best to first Download the latest Pro version of avast http://www.avast.com/eng/download-avast-professional.html and save it to your HDD, somewhere you can find it again. Use that when you reinstall.

Download the avast! Uninstall Utility, find it here and save it to your HDD.
1. Now uninstall (using add remove programs, if you can't do that start from the next step), reboot.
2. run the avast! Uninstall Utility, reboot.  If step 1 failed it may be necessary to run this from safe mode, once complete reboot into normal mode.
3. install the latest version, reboot.

[Lisandro]

Which is your firewall?
Other security program that could interfere?

[gdiloren]

I use ONLINE ARMOR FREE FW which had to update its program at the same time than AVAST. I had the same problem. 

[Lisandro]

Online Armor Free and avast start to be somehow incompatible.