Everytime I try to run the Avast Antivirus, it keeps going to a blue screen and locks up. Pretty sure I’ve got a virus but can’t find/get rid of it. Have XP if that matters.
Are you using Windows XP?
If so, please, go to folder \windows\minidump and send the newest (recent) .mdmp files for analysis.
Better if you can compress (zip) them and add some information about the BSOD and the link for this thread. 
Send an email to any of these addresses:
vlk (at) avast.com
rypacek (at) asw.cz
Or upload to the any of these anonymous ftp servers:
ftp://ftp.asw.cz/incoming
ftp://www2.asw.cz/incoming
Eddy’s links for minidump issues:
http://www.jsiinc.com/SUBJ/tip4900/rh4981.htm
http://www.microsoft.com/whdc/devtools/debugging/default.mspx