IE6 “Preparing to Install” Box

I hope this is the easiest question of the day. Everytime I open a new browser window for IE6, I get the message “Preparing to install”–it doesn’t say what it is preparing to install, but goes away quickly, and after about 1-3 seconds the browser opens and the rest of its performance is fine.

This is a reasonably quick Windows XP with all updates through microsoft update and no other evident problems. It is secured by one of the name brand anti-virus program, although this problem may trace to a recent overly ambitous update by that program. It also has anti-spyware installed.

Any ideas?

Thanks.