keyboard & mouse freeze sometimes

I have an old Dell desktop which will occasionally boot with a bios message that the keyboard was not found. After a couple of seconds it continues to boot, apparently successfully - Win XP. The mouse works for a second or two and then both the keyboard and mouse freeze up.

Rebooting fixes this, no bios msg and normal functioning. Reseating the ps2 plugs is no help. This happens maybe 25% of the time or so. What could be causing the problem?

 

Unplug your keyboard/mouse and turn on the computer, and see what it does.
If it's the keyboard or mouse, it should boot up, although it may give display a keyboard error message, or something similar.
If it does the same thing, it's not your keyboard/mouse.
It may be a memory error, as these are sometimes intermittent, and the computer does a memory diagnostic when you first turn it on.

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Another possability is overheating can cause similar problems. Does it occasionally go to a black screen and reboot? Does it do it only after the computer has run for 10-15 minutes?

If it is overheating, be sure the computer is not too close to the wall. If it is a desktop, the back and sides should be no less than 4 inches from an obstruction to allow for adequate airflow. If it is a laptop, be sure there is a gap of about 1/2 inch under it. The fans in the computer need to draw air in and blow it out.

If it is about a year old or sitting on a carpet, chances are that the internals are covered with dust. Dust acts as an insulator and traps damaging heat. If you are comfortable with opening up the computer, try blowing out the dust with compressed air. On a desktop computer, be sure to blow out the power supply as well (this is the large box where the power wire is attached)