windows computer disconnected from linux network

I have a storage drive running in my Ubuntu 10.04 system. I am working on a Windows computer that I need to copy data from to my Linux storage drive. I have the Windows system booted with the Ultimate Boot Disc for Windows and I have mapped the storage drive to a drive letter. When I start the transfer everything is fine for a few minutes and then Windows reports that the network drive is not available. Is this something that Linux is doing? If not, sorry for posting here... Thanks.