Check the folder <avast>\data\log
Are there any files called unpXXXX (where XXXX is a random number) or *.mdmp there?
If so, send them to vlk (at) avast.com
They may contain more information about the problem (maybe a link to this thread).
Please, go to folder \windows\minidump and send the newest (recent) .mdmp files for analysis. There is also C:\Windows\Memory.dmp file.
Better if you can compress (zip) them and add some information about the BSOD and the link for this thread.
Send an email to: vlk (at) avast.com
Or upload it to this anonymous ftp server:
ftp://ftp.asw.cz/incomingAlso, Control Panel > System > Advanced > Initialization & restoring Settings > Choose the dump options (removing the autorestart in case of failure)