WoW Freezing Suddenly

Well.. this is more for my friend.. I don't have the specs on his desktop but it's okay for WoW except for the part where it freezes.. According to him it's because it's old but I know for sure that it's better than my old desktop and I've had it since '04 his is from '07 but anyway. Mine's never frozen up like that and his freezes followed by having to alt+f4 and run WoW again. I know for one that he installed his own videocard and even he's unsure if he installed it right. But what I want to know is what the issue is, it's getting in his way in raids, lol.