When was the last time that you defragmented your hard drive? Seems like it has some bad sectors on it. Try booting up into Safe mode and see if you have access to command prompt line. When you go there use the chkdsk : /p /r command to repair your disk.
You could also try to extract your files through Linux Live CD since the problem might be hidden within your hard drive.
If you have a suitable PC company you can trust, bring your laptop to them in order to make tests of the RAM and cooling system because sometimes not enough cooling can make your video chip to work unproperly.
Hope this helps,