make a back up of all the contents of c:\windows\MEMORY.DMP and c:\windows\Minidump if you need and delete it.
open run command (windows key + r)
type "msconfig" without quotes and hit enter
go to startup tab and if you see any entry which has the word dumprep.exe uncheck the entry. when asked to reboot, reboot.
enable memory dump:
open run command
type "sysdm.cpl" without quotes and hot enter.
goto advanced mode
select settings in startup and recovery
in the write debugging information select small memory dump and click ok. and ok.
i dont know wether the settings needs restarting. if asked, do so.
next time you get the bsod, the minidumps should be in c:\windows\Minidump folder. upload it and give the link.
most probably it is avast system file which I stated previously. I can only say what caused the bsod. so that you can temporarily use an alternative and ask to get it fixed asap. avast team has to take a look at it.
nmb