After running about four hours, my computer screen blacks out momentarily and then repeatedly. The CPU continues to run and nothing is lost. However, key strokes entered while the screen is black are not recorded. It is not a monitor problem because I have tried several monitors and the same thing happens. I have a 586/133Mhz with CD, zip, and 3 1/2 disk drive. HD is 750 Mb. I have a HP printer and Microtek scanner attached to the station