Update to 3.1.3 stalls iPhone 3G

Hi,
I tried to update my iPhone to 3.1.3 this morning. All works well until the update process comes to the point where the silver apple is shown with the progress bar below. The progress bar does not change (i.e., it is not incremented). Nothing happens at all.
After I waited for almost an hour I rebooted the device and iTunes recognized the phone being in update mode and asked me to recover. I tried it (a couple of times), but it doesnt work. Same behaviour as described above.
Any suggestions?
Regards
Sascha
PC/XP Windows XP -