Iphone cant restore 3G

My iPhone 3G suddenly lost connection to the mobile provider. After a reboot i got the message Restore needed - Iphone cannot make or receive calls. Restore from iTunes.
I connected the iphone to my MBP to restore. After an hour or so waiting for the restore to finish i got an error message The Iphone could not be restored. An unknown error occurred (1002).
Ive tried DFU, different computers, different iTunes version (including latest). No luck. Always a restoring action for an hour, then error message, and back to beginning. Iphone only starts up in restore modus.
Anyone has an idea what do try next?
MBP Mac OS X (10.5.7) iPhone 3G 2.2.1