My PC is as follows:
1 gig of ram
Visteon HD radio attached to Radioshack USB to serial
120gig hard drive
Garmin 20x USB receiver
Running RR latest build and DFX4
Win XP SP3
I noticed when I looked into the device manager the com port and printer port were grouped together as 1 com port. I always have used hdpcr to test the radio, and it works with the visteon display as well. Other then that, I don't know how else to troubleshoot this problem.
The only reason this is an issue for me is whenever the USB to serial comes back from hibernate, it clears the winamp playlist. I searched in the other forums and found it due to a hardware issue, so I tried hooking it up straight to the serial port to see if that would fix it. Other then this, it's just an annoyance and the cable does work.