sudokusolver 0 Newbie Poster

i hv a assembled pc with p-4 processor 512 mb ram and 1.87 ghz with win xp sp2 installed in it. recently it crashed and i had to reinstall xp on my system after tht a queer prob has come up whenever i try installing some app/prog or using applications like wmp the app window appears and seems 2 work ok but then suddenly without a clue it disappears!!!!!! even when i try 2 terminate the prog using task manager it too disappears....... ny ideas wats happening?????????:(