Danny has an excellent write up on the issue with Firefox not being supported for the adCenter console as well as for tracking conversions. You would think that adCenter would get it working in a browser that is now widely used. Especially by the "early adopters" that want to beta test the product, all have to switch to IE to comply. Microsoft's response? Tell your customer service people to use IE 6 and post a message on your Web site to tell your customers to use IE 6 (or don't use the conversion tracking script).
What is extremely funny is that at the Search Engine Watch Forum thread, a couple people who upgraded to IE 7 can not sign up with adCenter, because only IE 6 is supported. So they either have to uninstall IE 7 and revert back to 6 or buy a new computer with IE 6 on it, because third party browsers won't work either.