Check: goto start, Control panel, system, performance, file system, troubleshooting.
make sure none of the list is checked (ticked).
I have experienced cd lock out when 32bit was checked!
otherwise, face the cd to you between you and a light source (do not look directly at strong light !), look for points of light comming through like scratches. this will cause a read error as will any significant scratch. sometimes rebooting can be delayed by muliple read attempts while trying to refocus 'around' scratches.
Neil West London