Strange...
The only other idea is that if you have any numbers in your pass, don't use the num lock pad to type them; use the numbers at the top of the main keyboard.
If you have any symbols in your pass, such as @ or ~, etc., it's recommended that you make a new password with none in the forum, as some symbols are in different places, etc. (make a pass with only letters; no numbers is recommended too).
If neither of these work, then you'll have to stick to your old account or make a new one. Not much else you can do. :c