Windows 7: Explorer Freezes At startup and Randomly!!

heloo guys i am a new member here someone from another forum refered me here for my folowing problem

1] whenever i try to play a VIDEO on windows media player the windows hangs and the system too.. the only way out of it is RESET..
[2]secondly everytime i start windows after about 5 secs the windows explorer hangs for about 2 mins... the taskmanager doesnt work either...
and some times even randomly while i am using pc the same thing happens



i have NOD32 in ma pc which is updated daily
but
i have also scanned my pc with many online scanners like KASPERSKY online scanner etc but no Viruses found...

now i m using VLC media player for all Videos etc...
but cant find any solution for windows explorer hangs...
its getting messy day by day... PLZ help me..
WELL can anyone help me or getting teh same probs..
and kindly dont tell me to do a clean format and reinstall my OS cuz i cant afford that...

i have windows 7 ultimate build 7600


my system specs