WMDC blocks Samsung Network Scan Utility in USB mode

I am using Samsung's Network Scan utility to scan documents from a network
connected multifunction device. This works well, as long as no mobile device
(HTC Touch Diamond, WM 6.1 Professional) is connected to the PC using USB for
Synchronization. When I connect the device to the PC using the USB
connection, the Samsung Scanner status changes to offline, and no scan is
possible. When I disconnect the Phone, the scanner goes online again.

When I connect the mobile device using Bluetooth for Sync, the scanner stays
online.

Samsung tells me (of course), this is not a Samsung problem, but a problem
of the software of the mobile device. But maybe, they are wrong, and this is
related to the Firewall (Norton Internet security 2008)?

Does anyone have the same problem, or knows how to fix it (maybe port
settings?).

Thanks