littleb,
Try resetting the stored passwords for those pages if you have not already done so. Perhaps on the first time around the wrong pass was entered which mozilla/firefox now continues to use on your home computer. The password manager is found under the tools header. It can show the present passwords for each stored site so you can verify their accuracy. If it is incorrect, delete the entry and try again.
That's about all that comes to my mind on this problem.

"Those who preach the myths of audio are ignorant of truth."