yo. sup! ay everyone.

Last last Christmas (2004) i got my mum an Nokia 3120 prepaid phone. Now i unlocked this phone my self from the Australian Optus network and it worked fine. The phone has been very well kept and never damaged, although just recently it has started to freeze up and shut down. This usually happens while writing a text message or just after a call. The screen will black out and the phone will turn completely off.

When restarted it will usually mention something about an error occurring due to the sim card? Also some contacts will not be listed in the contact list? Does anyone know what could be the cause of this problem?

I have tried many times, cleaning and ensuring the sim card is correctly positioned and that the battery is correctly inserted?
This phone has JUST ran out of warranty, so wanting to know what i could do.

any help would be greatly appreciated!
Thanks alot.

that happend 2 me wen i didnt unlock mine properly u need 2 take the fone 2 a pro 2 unlock it it doesnt cost much and it then wil be properly unlocked,,, listen carefully now..... then insert the sim and save every contact 2 the sim and do master reset and turn it back on and the fone will be like u jst got it