Okay.
Perhaps I should go for the obvious option. Under Options, Security Tab, check that "Remember passwords for sites" is ticked.
If it is, next check, on the Privacy tab that "Remember what I enter in forms and the search bar" is ticked.
If it's still not working, check the exceptions on the same tabb, make sure TalkChelsea isn't in there as blocked.
If it's not, look below at Private Data, make sure "Always clear my private data when Firefox is closed" isn't ticked. Probably best to have "Always ask before clearing private data" ticked too.
If none of that works I'm not sure what else can be done to make it work, but I'm pretty certain it's a problem at your end because I don't think anyone else is experiencing this problem.