Running Random Programs Fatal Execution Errors - Shut Down

my computer is weird to the max....here are some problems just to name a few: when running random programs, i get fatal execution errors, i get messages asking to debug random apllications or terminate them, i get messages to just terminate things, i get messages that start coming up whenever i try and open something and whatever i try and open it says it has to close....sometimes my whole screen turns blue with white typewriter font saying i have hit a problem and i need to shut down (blah blah if the problem persists contact blah blah if this is the first time uve seen this error just reboot blah blah) sometimes my computer locks up and i get stupid errors.....they tell me to send error reports, that does no good.....i get them 24/7 too....basically im getting error messaages with lots of zero's / name files in them and my only options really are to terminate things (things being applications im trying to run).....this varies from aol instant messenger, to games, to internet browser, to word, to paint....anything....ive run ad-aware, spybot, mcaffee, ive checked my hijackthis logfile and deleted unwanted things.....ive run chkdsk on bootup, ive run defrag, ive run system restore idno how far back, ive run clean disk, and other stuff.....i think most of these problems have started once i downloaded the service pack 2 package from