OK, so after you restart the browser, do all the groups and accounts appear in Advanced Options->Accounts tab? If so, that means the import really did work. There's no reason you should have to do this, but do you still have access to your Windows XP PC to compare account settings manually?
I use both Windows XP and Xandros Linux, and have no problems importing/exporting settings to and from both machines. Is there any chance you're simply not using the same master password?
I'm grasping at straws here...