AFAIK the GPS can't get a fix unless the time is correct. If A-GPS server is not available either due to not having CSSU, not having the Nokia SUPL server in settings, no phone signal or WLAN the device cannot update the time.

Sounds like you need a new backup battery for your device. There are replacement capacitor types listed on here.
http://talk.maemo.org/showthread.php?t=90864