I hope you forgive me for being a bit flippant but your reply to my post was a little silly.
You wrote:
i think that you should have a check which hardware device contacts com port 3 on the box...
That was exactly my question!
I wrote:How do I tell whats using com port 3 in Vista Home Premium?
I resolved the issue anyways.
I used a serial port program that closed the program using the port, then when I opened the program that needed that port,it "captured " it and now the program runs fine.