I hear you.
I normally use FireFox with NoScript and AdBlock for most browsing. However, I have been using SandboxIE with a specific sandbox for financial institutions. Mainly for historical reasons from years ago when FireFox wouldn't work. I have a separate sacrificial sandbox that gets cleared regularly and never use IE unsandboxed. This is the first time I've run into problems.
I will be re-evaluating my approach, though.
The disturbing thing is that once I logged in with FireFox, my dwolla transfer I had been waiting on was there. I've changed my passwords on many locations and am looking to make some other changes. It could be a fluke of timing, but it really bothers me.