Vista - Vista problem

I'm new to vista. I just got this new computer this weekend. It has a AMD quad processor, with 4gb ram 640 hd, vista home premium. The system boots just fine and runs great on most websites, until I log on to craigslist. I can view maybe 5 or 6 adds, after that I can pull a add up but no pictures, if I click back it will go back, but then it will search for but not open anymore websites, and I have to do a hard restart. Has anyone else experienced anything similar, that was related to one site. any ideas on fixing the problem Thanks

Does the same thing happen if you boot to [safe mode + net] and attempt to access Craigslist from there?

Not sure, I'll try it tonight when I get home. Thanks

It doesn't seem to have any problem when I open it in safe mode + net. I also know that it's not just craigslist, if I open several websites in a row it will lock up. I also believe I have narrowed it down to my Antivirus, avast, if I disable it, everything works fine. Is there a known problem with avast and vista that I'm not aware of? Could there be some programs running in vista that are causing the problem and could be removed. Any thoughts?