When I try to connect the pma to my pc, the computer says the midi port is being used by another device. I know this isn't true, and it's a new computer with no old drivers. I have tried both com 1 and 2 but to avail. Is there some trick I am missing?

WOW!
Well I can certainly speak from experience, since about 10 minutes ago I (finally) successfully regained PMA connectivity. I had to take my system down and reinstall the convertool program (I'm lost without it!)
Here's the deal: First, doesn't matter what your PC has in it, you have to go to RolandUS web site and download the current Roland serial driver, especially if you have WIN98. It won't run without it.
If you already have done that, then it could be you haven't selected the Roland driver in your midi settings (although the installation of the new driver should do that automatically.) So go and check in Control Panel/Multimedia/Midi and make sure the Roland driver is selected.
If it is, lastly, you should be able to at least open the program. Then go to "settings" and make sure that the ROland Midi driver is selected for both MIDI OUT and MIDI IN (That's where I slipped up!) Then you should be in business!!
Write me if you still have problems!