For months now I've been plagued with the erratic shutdown of my computer and the appearance of the "blue screen of death". A suggestion from Microsoft recommending the checking of hardware put me on to checking my memory cards (2 of 256 mb and one of 512 mb). I did the checking with "Memtest". When I checked with all three slots occupied, I kept getting error messages (at address ffffff7f) so I tried each memory card individually, each one separately in each of the three slots: all checked out to be faultless by themselves and in twos. However, when using all three slots together, I get the memory error message--no matter what order they are placed in. Right now, I'm working with only two cards (512 and 256) in slots 1 and 3, with the middle slot empty. Running Memtest showed no problems.
Is this "proof" of a faulty motherboard (mine is an Asus P4U800-X)? If so, is a fault like this covered in the guarantee?