Deleting the com port is good, but if you have a device that uses it, it will just grab it up on reinstall when you reboot. Again, is the port open? You might try to add another port. I don't recall how to do it, but that's what I did long ago. There are also threads about that.

I also recall that the Belkin seral-to-USB worked for me, and the highly-touted Keyspan did not. Others had the opposite experience, so it's highly dependent on your setup. [You drove 1 hour--in this world of on-line commerce? Man, I thought I was impatient!]