I had this very problem on the weekend and I believe it has something to do with either installing the new gnome stuff, or gtk? Anyway, what was happening was while using evolution I'd click on a link in an email an *poof* "sig 11". Opening a directory in xmms would also cause it, along with changing font colors in any gdesklets display. I couldn't seem to fix it and no one else had a solution ... however a fresh re-install from scratch seemed to fix it. I sense it's a configuration issue and my googling has turned up some insight.
This has happend to certain people with bad or corrupted fonts. I couldn't find a solution that way either, but if someone knows how to solve this, I'll buy them a beer