Have you tried to re-install your Operating system from the CD supplied with the machine?
Switch on the machine, open the cd drawer, insert the cd, then switch off the machine, switch on the machine again,and hopefully it should re-boot, and re-install the operating system.... if not, you may have dislodged the chip or memory on the main board, which may need the services of a "tech guy"...
Gerry, April 2009
