I have many serial devices installed on my Windows 7 PC. I also have a NI PCI-8430/8 (RS-232) Interface. The COM port numbers were getting a little messed up (most low numbers showed in use even though they weren't present) so I wanted to reset them all and try and organize them. I cleared the port asignments in the registry in HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\COM Name Arbiter ComDB
Worked great mostly. Every serial port could now be set to what I want except the NI hardware, they stayed on what port they were and the drop down is greyed out.
