In uk.d-i-y, John Rumm wrote:

How many DIMMs do you have fitted?

If more then one, you could try running with only one device fitted for
a bit - then swap to the other and see if that has any impact. If it's a
memory problem then its unlikely to be a fault in both devices.

If only 1 DIMM, then buy another one the same and try that (RAM is cheap
enough at the moment!). Even if it does not fix the problem you at least
have an upgrade for your money!

Rather less invasive, and usually at least as effective, is to run a
good standalone memory diagnostic: and the greatest of these is memtest86.
See www.memtest86.com - despite the .com it's GPL'd freeware. You download
the entire binary and put it on one floppy or write a bootable CD-ROM
(instructions on the web page), and instead of booting Windows, Linux,
BeOS, or anything else, you boot into the specialised memory torture test.
I've tracked down obscure and 'orrible incompatibilities between RAM
sticks (or even sticks temperemantal about which slot they sit in!) and
Athlon motherboards with memtest86: recommended. Like I say, requires
none of those heart-stopping "put the DIMM in firmly, no not *that*
firmly" moments, and pretty authoritative in tracking down bad RAM -
if you can run 24 hours of memtest86's "thorough" tests without a fault,
your memory system has to all intents and purposes a thoroughly clean bill
of health.

Well (ob. d-i-y), it is fixing-yourself, rather than taking-it-in-to-be-fixed
;-)

HTH, Stefek