What does their customer service say?

Just a thought... How long between logging out and trying to log back in? I've heard that some sites only allow so many log in's in a set amount of time. Especially some of the ones with more strict security protocols.

Next thought.... it's possible that the bank's system doesn't recognize your computer which sets of warning alarms. I run into that with my photo processing software. One time I can log in & it works perfectly. The next time, it may work or it may tell me my password is invalid and I have to contact the company to have them reset my account (because it won't recognize my purchase ID either). I've had to have them reset it so many times it's not even funny. (And it ticks me off every time!)