dear friend just cool...
follow these steps. i think this will help you ...
after start yout lappy and starting explorer process..
then open cmd after that type- chkdsk /r /f press enter
it will ask u yes or no press y and press enter
after this process reboot your lappy normaly..
then it will check system tottaly while pc start up.
dont abort that process... it will say press any key to abort checking but
dont abort it .. it will check all system . it will take 30 to 50 minutes depending
on pc hardware....
after completing system check process ur pc start windows
that sit ur problem is solved ...
if the problem continues then insert windows 7 cd in pc and go to cmd
and type - sfc /scannow press enter
it will check all system files after reboot i have guranty ur problem is solved