Here is info I received on the DXLab group from the author about Commander showing an 8020 error in the debug file when trying to run the RR Micro:
An "8020" error says that the driver issued an interrupt saying "there is data waiting" before the data was available. The application tried
to read the data but received no data. Specifically, it's Microsoft's MSComm component that does not tolerate this driver defect.
So, it looks like software written with VB will have problems with the drivers being used in the RR Micro product unless they are changed to avoid the "data waiting" problem.
Update: I was directed to a Microsoft support page that discusses this problem. Here is the link:
http://support.microsoft.com/kb/318784Joe