I'd check the power supply, do you use higher res then 800x600 ? If the pc is rebooting itself, it may revert to 800x600 res, that would cause your icons to get all jumbled up.
but I'd check out the power supply before you do anything drastic, a bad power supply will cause the pc to shut down, and show a black screen.
You can pick up a new power supply for 9$
oh, it's a laptop ?
I'd take it back if you can.