Dijkgraaf - 1:26 am on Nov 4, 2010 (gmt 0)
Looks like it is actually something Google related. Probably Google Toolbar (GTB6.6).
I embedded the whole thing in html (see example below), and what you then see is a picture of a question mark, a minus sign, a check box and then the small square Google logo (like the favicon) with a magnifying glass.
<img alt="Embedded Image"