you have to check all the possibilities...
start from Virus scan...
then,
open DOS (command) window and type this:
chkdsk /r C:
press enter.... press yes for any prompt... it will tell you that it will run once you restart the computer....
so restart the computer.... and you will see chkdsk repair option will start running with blue back ground..... it should have 5 steps to run... and could take atleast 2-3 or even more hours (depending on your computer/hard drive specs) ... it will repair any bad area in your hard drive.....
report back once you do that
