Sorry to be so long, I've found the info about the DSO exploit and Spybot. It's to do with Spybot, not Avast.
If this is what you're getting
DSO Exploit: Data source object exploit (Registry change, nothing done)
HKEY_USERS\S-1-5-18\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\0\1004!=W=3
DSO Exploit: Data source object exploit (Registry change, nothing done)
HKEY_USERS\S-1-5-21-117609710-764733703-1060284298-1004\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\0\1004!=W=3
DSO Exploit: Data source object exploit (Registry change, nothing done)
HKEY_USERS\S-1-5-20\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\0\1004!=W=3
DSO Exploit: Data source object exploit (Registry change, nothing done)
HKEY_USERS\S-1-5-19\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\0\1004!=W=3
DSO Exploit: Data source object exploit (Registry change, nothing done)
HKEY_USERS\.DEFAULT\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\0\1004!=W=3
You need to read this page for the fix -
http://www.askmehelpdesk.com/cgi-bin/yabb/YaBB.cgi?board=computers_for_beginners;action=display;num=1082096807