Programs stuck on taskbar.

How can I fix the problem of applications that are
minimized on the taskbar and if I click on them they don’t
get restored. My work around is I have to right click on them and say
maximize or restore. I don?t know why they seem to be stuck down there.
Any clues!
I shouldn’t have to double click or use Alt+Tab.
I have SP4 now and still not working.