The complete reinstallation isn't a solution! The problem still exists!
Sorry to ask you again, but right now, do you have anything usefull into avast logs?
Right click the 'a' blue icon and choose 'avast! Log Viewer'.
Into the reports (<avast>\Data\Reports) do you have anything related to this error?
Do you have any file into \windows\minidump folder ?
Can you send the newest (recent) .mdmp files to vlk@avast.com or rypacek@asw.cz for further analysis?
Better if you can compress (zip) them and add some information about the BSOD and the link for this thread.
Alternatively, you can upload the file(s) to Alwil anonymous ftp servers:
ftp://ftp.asw.cz/incomingftp://www2.asw.cz/incoming