iPhone 4s error -1 when restoring in itunes

Hi everyone!

Since 3 days I try to restore my iphone 4s in itunes but it does not work.

It started with the problem that I did not get connection to the mobile net.....

so I tried to restore it in itunes 10.6.1 with firmware 5.1.

I followed all advices (no firewall, no virus detection, change hosts)

Anyone an idea ?

Thanks,

Thomas