"already running"

[Guest]

For several days, I find that a little window suddenly
pops up on my screen that simply says "already
running!"

I just click on the "x" and it goes away, but then it
comes back, sometimes just moments later, sometimes
longer.

And when I leave my computer for any length of time,
those little windows accumulate on top of one another so
that I have to close a dozen or so of them when I get
back to my desk before I can do anything else on my
computer.

What's up?

 

[Kevin]

Virus? Worm? Trojan?