Check the video and memory cards to make sure they are properly seated in
their slots. Disconnect the IDE cable from the hard drive and then
reconnect it to make sure it has not loosened. If it is a SATA drive, be
very careful, the connectors are breakable. Disconnect all the external
devices except the keyboard, mouse, and monitor. If there is more than one
memory card, try running with first and then the other to see if memory is
the problem.