help!!! restarts when i click exe.

i recently downloaded some files ina rar. when i unpacked them and tried to click the exe file...the computer restarted. actually with one single click the screen went completely black and started booting up from bios. this cant be a windows error can it? it wasnt the file because i tried downloading some others and all the exes do it. has anyone heard of this? could it be my motherboard or hardrive or powersupply shutting off. please help me...because there is not log or info of anykind this is the only way i can get help. thanks...greg

(running xp prof.)