well it doesn't sound like what i had, Hades might be right about graphics error or some other system error. Try Hades idea of lowering settings....do you need to know where those settings are?? also if you have a dual or quad core vista doesn't like to use them unless you you tell it to.....there is a setting for that aswell.
i would try 2 things id Hades suggestion turns up nothing, a malware scan and re-install.
too much malware and adware can really do alot of harm and might be crapping things out. Or maybe some corrupt files for that area.
if that doesn't help you might need to have a deep-scan diagnostics or a benchmark test made.
