Yes, we have the same problem, and it also happens in CB 1.1.
I tracked it down that it IS a Joomla issue, not a Fireboard, CB or any other plugin/module/component that requires legacy mode in Joomla 1.5
The problem turns out to be the legacy plugin is activating before the remember me plugin can work (even if you do have remember me before legacy plugin in your adminback-end).
Here's the bug tracker link I logged with Joomla, they've given me a patch which I've tested and has fixed the problem. They didn't believe me at first, so please sign up for a free account and add that it fixed your problem. You can also reply here as well if you like for other fireboard users to discover this fix. I really am surprised no one before me sorted this out, it took some effort tracing it (at first I thought it might have been a CB bug), then proving it to Joomla.
joomlacode.org/gf/project/joomla/tracker...racker_item_id=13662
AJStevens