Freezing on menu selection?

Samsung NC20 netbook, XP SP3.

I sometimes get a complete freeze - nothing other than the power switch
has any effect. (Usually, it comes back up having lost nothing, but it's
obviously frustrating.)

I would suspect a hardware fault, but it seems rather too often for
coincidence (possibly always) to happen when I'm selecting something
from a menu, usually second or third level. By selecting from a menu, I
mean: Start, Programs, then go into one of the sub-headings under
programs, drop down (or pop up) a list, select one - freeze. Or, in an
application, select something from the menu bar, down to an option that
has a sub-menu, go into that, just about to click - freeze. I know it's
happened immediately - not only does mouse movement stop (that happens,
of course, briefly, under other circumstances, when the PC is busy, but
it comes back), but parts of the menu(s) from which I'm selecting hang
about on the screen.

It can go for ages (days) without doing it, then happen two or three
times in one day.

I've just done a full system scan, which found nothing (except in a few
..rar files I'd downloaded but not unpacked, not yet having a .rar
unpacker, so I don't think it is those). My checker (AVIRA) is up to
date. I also have a firewall. And always scan any executable (or .zip) I
download.

Anyone else have this? It does feel like a hardware fault (I've had the
machine since May 2009 or so), but the frequency with which it seems to
be associated with menu selection seems odd. (And if you have, do you
know what causes it and how to fix it?)
--
J. P. Gilliver. UMRA: 1960/1985 MB++G.5AL-IS-P--Ch++(p)[email protected]+Sh0!:`)DNAf
** http://www.soft255.demon.co.uk/G6JPG-PC/JPGminPC.htm for ludicrously
outdated thoughts on PCs. **

"To YOU I'm an atheist; to God, I'm the Loyal Opposition." - Woody Allen