Trouble Syncing iPhone 3G

I am having trouble syncing my iPhone to my PC. When I plug it in Windows recognizes the device and starts iTunes. Sometimes it will start to sync. Other times it will not see the iPhone at all. Either way I seem to get one of two alert windows pop up. One says, iTunes could not connect to iPhone because an invalid response was received from the device. The other alert I might get says iTunes could not connect to the iPhone because an unknown error occurred (0xE8000065). The alert boxes actually show the characters. On the occasion that iTunes actually sees the device it does properly identify it. The device will make the connect/disconnect sound repeatedly. Typically I see nothing happen on the iPhone, though sometimes it will simply reboot itself.
The iPhone otherwise works without any problems. I can sync my other iPods to the same PC using the same cable and USB port without any issue. I have tried uninstalling/reinstalling iTunes, and completely wiping the iPhone. I could try a restore, but I would fear that the connection might drop in the middle of it.
Any ideas or help would be most appreciated. Thanks!
PC Windows XP Pro