Firefox Goes Glacial?

Okay, I’ve had it. For some reason my office install of Firefox has become glacial. It takes upwards of 25 seconds to start, and there is a lag in most actions when using it. I have completely uninstalled prior versions, removed all extensions, and then reinstalled version 1.5 a number of times, to no avail.

Anyone have any ideas? I need ’em.

[Update] It’s working again. Something went kerflooey (and I use that word in the  highly technical sense) in the relationship between Sophos’s antivirus app and Firefox 1.5. In other words, it was all Steve Munford’s fault. So Steve, this was all because I didn’t  make it to London before Christmas, isn’t it?