Mysterious P op-Up!

Ever get one?

[Heartlander]

I thought I saw something about a week ago and just decided I probably needed some sleep.
Today, I realized what I saw- a pop-up on my site that I cannot identify the source of!
My server is private, so that's out.
The only ad banners are from Chitika and Adsense.

Has anyone ever experienced this before?
Is it actually my web page, or some kind of spyware or such in my computer?

Thanks in advance for any and all help.

[edited by: txbakers at 3:00 pm (utc) on Nov. 20, 2005]
[edit reason] no personal URLs please per TOS [/edit]

[stapel]

Looking at the image, which part of the capture is the unwanted pop-up? Is it the neon green thing? I can't read what it is....

Have you scanned your system with an up-to-date anti-syy- and/or anti-mal-ware program?

Eliz.

[Heartlander]

Yes- it's the neon green banner in the upper left corner.
Haven't scanned for that kind of intrusion yet, but I'm on my way......

Is this common?
I have never seen such a thing before, and I'm online A LOT! LOL