Just cleaned the heatsink and now the computer shuts off :(

No i did not, unfortunatly on a sunday after 7pm radioshack is closed. but ive never had to apply any before? why would it matter now??

Not only is the compound required but removing the heat sink and putting it back on can leave air voids which do not conduct heat well.

-> How would you propose you bring a new tech up to speed here?
Bob

I see. i thought and feared it was something to do with the fact that i washed it in the sink, and i just took the heatsink out and put it back in and it SEEMS to be running... its still at around 83 C though... i assume once i get thermal paste and a better computer case (which is on the way) it should cool down more? also what would be acceptable temperatures for a CPU?

All I know is that as the temp goes up, the life span goes down and if it's too much, you see very odd failures.

So odd that you find folk reloading the OS, scanning for virus and all it was, was a buck's worth of compound all along. You will encounter new techs (they don't stay shiny new for long!) that want to debate if the compound is required.
Bob

had a thermal pad pre-installed. If and when the HS fan is removed, then you must clean the surfaces and reinstall fresh thermal compound. Otherwise the CPU runs hot and may shut down to protect the CPU from burning up.

VAPCMD