I have some extrange behavior with "user/password remember utility" (please excuse my bad english) when trying to access Gmail (weird! Don't U think?)... The browser simply does not remember my Gmail account... Maybe because I have another Google (Orkut) account... But with Mozilla's Firefox I have no problems with neither one.
In other cases I have two user accounts on the same website and I have the same problem.
Again confronting with Firefox I love when 'dobleclicking' the user field the browser simply suggests a list of possible usernames for you to select the appropriate one.