Programs freeze at random then come back a few minutes later... no viruses detected?

I have Vista, everything is on auto updates and I don't have anything on startup other than what I absolutely need. I have run CCleaner (the cleaner and reg fixer) and TrendMicro Housecall which found no viruses. I use FireFox which sometimes freezes or moves slow but it also happens to other programs. I can still play games and sometimes I won't have issues for hours on end but when I do it is horridly annoying. I purchased this laptop new in December and this is the first issue I've ever had with it. Any suggestions? Freeware or programs I should purchase? Please don't suggest using Norton... I really don't like it one bit for my own personal reasons :)