Launching/clicking in Firefox OS X opens Firefox in Parallels (XP)

I have done something to my system that has caused the following behavior:

Opening Firefox in OS X will start up Parallels and open the VM copy I use for IE6 (I also have one for IE7 and it does not open) in coherence mode. If I close Parallels and then just click on a page in Firefox OS X, Parallels will start again and open Firefox. Firefox opens to the start page, not some page selected or clicked on in OS X.

Parallels has been running fine for months. I obviously did something to change this behavior. I can't find anything about this problem. Any ideas?

Parallels version: build 3214 (June 21,2007)

Thanks!

Peter