hmm.. I have alwasy been a bit skeptical of USB to serial adapters I have saw int he past that some work and some not so well. Now that I think about it the last blue tooth adapter I used actually connected to the RS232 port and as one would expect it was a single port to send and receive. Did not have any issues. I also code on mobile devices that have bluetooth but to my program it is just a serial port and again only 1 port which handles bidirectional communication as a serial port should.

I have no idea why your adapter would need or want to use a different port for sending from that for receiveing but I suppose there is a reason. Have you tried the dongle under Windows 7? On a different PC, different USB port, different hardware dongle?

Does not seem like the problem is related to VB nor the Comm control