Icons lost for Notification Area on Task Bar

Several Icons, including the "Safely remove hardware" and the "volume" icons,
are now missing from the notification area on my Windows XP task bar. There
are simple instructions in "Help and Support," but for some reason they will
not work. Once I plug in a USP connector, I cannot remove it "safely"
because that icon is missing. IF I can find the file in Windows Explorer
(File Manager) I can tell it to "Eject" and it apparently "lets go safely,"
but sometimes I have trouble with that. I can't help but feel there must be
a simple explanation and solution for this, something stupid I have done, but
I have tried off and on for days and cannot get it back. I would appreciate
any suggestions.
--
Taron