The previous owner of this laptop had an unregistered version of vista home and many virusrs/corrupted data. So I installed avast to remove the problems but still ran super slow. So I tried to install my copy of xp pro since I have a disc with drivers for this machine. The computer wouldn't allow me to downgrade even by booting from cd so I used the hard drive as an external in another computer and formatted to remove previous os. Now when it asks to press any key to boot from cd and I do as it says the message (checking hardware configuration) comes up for a second then disappears. The screen stays blank forever afterwards. Any ideas?