COM 1 Held Open

I have a new HP LC2000 Netserver running Windows 2000 Advanced Server. I have two modems for dial up networking installed on COM 1 and COM 2. Since installation the COM 1 refuses to work. When I try to run modem diagnostics Windows says the port is already open. I suspect something grabs the COM 1 port during boot up but am at a loss as to how to find it. Can anyone help?