As indicated in the manual,
never
register a desklet without testing it first, since it
prevents you catching potential error messages due to
improper configuration, etc. SystemMonitor is undoubtedly a
desklet you want to test "manually" from a console, as the
error messages help you see what is not tailored to your
system; same applies to mailer.
So fire-up a pseudo-terminal, kill your desklets
(
adesklets --killall, go to
your problematic desklet directory, and start (t)esting. If
you don't understand the error outputs, refer to the
desklet-specific topic on this forum (in
About existing desklets). There is a
fair chance an explanation will already be there for most the
problems you might encounter. Yours,