Everything in xp crashes. why?

my computer keeps crashing whenever i use internet explorer, firefox. also in games too. i play nba live 08 and oblivion etc. i get this stupid send/dont send pop-up then the program crashes. a few mins in youtube then boom, crash. its kinda irritating, so does anbody know how to disable the error window thing so i can continue with what im doing even if something in the program fails? i hope thats possible. im using windows xp with 2 gig ram, an 80 gig hard drive and a 40 gig hd. geforce 7300 agp. two power supplies cuz the geforce eats up a lot of power. any solutions? thanks