Windows 7 mapped drives disconnect with red X

I have a perplexing issue happening. I have a 40 seat environment with MS SBS 2008, 2x Server 2003 Std SP2 for file/print/apps, 39 XP Pro SP3 desktops and 1 Windows 7 Enterprise 32-bit PC. My Win7 machine is losing its connection to mapped drives from the 2003 servers. They are still listed but they have a red X over them and when you try to open them you get: "Error occured while connecting to \\server\drive, Microsoft Windows Network: The local device name is already in use." The only way to restore the connections is to reboot the PC. Just logging off doesn't work and neither does trying to manually run the logon script or manually mapping the drives.

All other drives, even if they say disconnected, will open right up by clicking on them. All my XP machines stay connected and are having no issues at all with drives from any server. I did a "net use Q:" on the Win7 machine and it came back normal, just disconnected. Same with the other mapped drive letters. I have seen multiple posts on the web and technet about this issue but no one seems to have solved it yet. I would like to sell the VP on Win7 but this one issue is making it difficult. Other than this it works great.

Thanks in advance for your help,