usb mouse problems: etch/gnome/metacity

[cs <cs@networkingnewsletter.org.uk>]

I've not managed to define precisely when I get borrows but I'm noticing
the following symptoms and was wondering if some kind soul would help me
debug what's going on in order to get to a solution? Thanks, Michael

set-up: etch, gnome (eg gnome-core 2.14.3.6), metacity 2.14.5-4 and
Dell/Logitech USB optical mouse (seems to work fine in WinXP), with
nVidia graphics card/TwinView and 2 monitors (diff resolutions)

symptoms (occasional and not sure how to repeat)

a) double clicking won't select anything
b) in evolution, clicking on a new message or folder has no effect
c) the cursor (arrowhead) disappears - if I set prefs to show cursor by
depressing 'CNTL' I get the moving rectangles but there's no cursor
there)
d) focus doesn't move to new window (as it should and usually does)

I think the following is also a symptom but not 100% sure:
e) doing ALT-TAB to move between windows does nothing on very first
ALT-TAB

Any thoughts???
Or am I just going mad, slowly??

Thanks, M