After being blocked for certain unknown cause, it?s recommended to analyse your hard drive, to detect eventually the errors of your files system which took place, and correct them.
To do that, go to:
My Computer > right click on the wanted partition/disk > propriety > Tools tab.> Verify now.
That?ll open a small dialog box. You can check both options in it, and start.
Notice that, if you like to verify the disk where ?Windows? is installed, the verification will not take place till you restart your computer the next time. It?ll be done automatically, and probably will correct the errors? cause.