Windows Vista forum: "This program not responding"and screen frezes in startup

am using dell studio xps 16 laptop with windows vista 32 .recently i waas downloading some torrents and had not switched off my laptop for 3 days..when i finally switched it on the desktop shows and then no response.just the loading logo (blue circle)..i can click on only MY COMPUTER logo in my desktop..and can access the drives .but when the left is pressed the lading logo appears again..basically i cant access any shortcuts other than MY COMPUTER.i tried to click on organize drop down menu to c if any hidden files like recycler or something.but then again the screen is stuck with
that blue logo.
i used ccleaner to do the necessary cleaning ( in safe mode of course).used system restore to go back 3 days and still no result..
i have done even a virus scan with the latest update of avast ..but no use..
when the desktop appears and i click on start it says that this program is not responding and it would if you wait for sometime..when i click on ok the screen freezes and it never responds.i have even done a malware scan using malware bytes but still no result..is there any other way to fix it other than re installing windows?