blinking taskbar buttons

Strange problem....

I'm having trouble switching between programs via the
taksbar. The behavior is erratic. Sometimes clicking on a
program to maximize it from the task bar starts the
button blinking. Other times, it switches to the
highlight color without blinking. Rarely does it actually
maximize that program as intended. Alt-Tab seems to work
properly. Another possible clue: a right click on a
taskbar item does not open up any list of choices (like
close, etc)

Suggestions?

Thanks in advance