Updated my browser yesterday, and after a quick search this morning I think that may be the very root of this problem.

I have five email accounts I check every Monday. The first four worked fine, but at the fifth one the progress bar froze and I couldn't get any further. Tried viewing my inbox in regular HTML mode, and that worked fine, but when I tried switching back to the more flexible regular view it froze again. Found this URL on the Mozilla forums, and it works great, though it probably doesn't solve the problem. I have quite a few plugins installed that might be interfering, or maybe a virus. I hope it's option three though, a simple bug that either Mozilla or gMail will quickly squash without much bother so I can go back to fluently surfing my webmail without the use of artificial URLs.

On a second update and email login, it seems the problem is no more.
Confusion strikes me like a serenade of napalm.