Expect 3.0.3 soon, probably next week due to this...
QUOTE
Shortly after releasing Firefox 3.0.2 our QA and Support teams began
seeing reports of problems certain users were having with the Firefox
Password Manager. This was being caused by non-ASCII data (in domains,
logins or passwords) saved as something other than UTF-8 failing to
convert back to Unicode (see bug 454708) which was a regression from a
fix to make the Password Manager work on IDN sites with characters
over U+0100 (see bug 451155).
Read the whole story
here (a google group so you probably need a google account to read it).