Same here...

10.06.2009 06:53:59 - WARNING [java_downloader] ->
Error occured- latest:ERROR_FATAL
00000000000001100000000000000001 <Statuscode
00000000000000100000000000000000 |ERROR_FATAL
00000000000001000000000000000000 |PLUGIN_IN_PROGRESS
00000000000000000000000000000001 |TODO
00000000000000000000000000000001 |VALUE_ID_PREMIUM_DISABLE
StatusText: Verbinden...
ErrorMessage: Passwort falsch

Mediafire doesnt ask for a password and there is no limit as far as i can see.
But if i try to download the same file (and same link) via JD it asks for a password.

Its this way with every Mediafire link i tried so far.