has anyone seen this before?
I believe so. It sounds like you are using the original PLX-DAQ, which has a limited number of COM ports that it can address. It may be possible to configure PC to host bluetooth on a lower COM port, but I have never pursued that. I raised this matter with NetDevil when PLX v2 was coming out, and I believe it was fixed. If you are using V2 and it has not been fixed, talk to NetDevil about it. I got the impression that it can be easily fixed. While I believe PLX v2 is one the most significant contributions on this forum, I have never actually used it as the original is fine for me anyway and, now that I use bluetooth, I find Bluetooth Graphics Terminal a better option.http://forum.arduino.cc/index.php?topic=437398.0
You are clearly not using PLX v2 - yet - so, are you aware that the original PLX will not work with Excel later than Office 2003?