If you have problems syncing music, pictures, or other large files in which the connection suddenly closes, there may be an issue with a serial driver that is installed on the device. Unless you are using a VPN server or a firewall that is blocking your large files from synchronization, you may try switching your device into RNDIS mode to fix your large file sync problem. If your device has a USB to PC option, you might use this workaround:
Using Activesync With Vista