computer Hanging

Hi
I have recently been having hang problems and it seems to be getting worse. I have used regi cure, trojan remover, driver update, security manager. they had found some bad stuff, but that has gone, i have done scan disk, defrag, and chkdsk, no problems. i am running out of ideas on how to resolve this frustrating problem. just to mention after i have done a defrag, i will have 0% left, but after a few hours usage it would of defragged to ??gb, surly this can’t be right? It would be much appreciated if anybody can help on this issue. Cheers Mickylearjet