Did you ever get any help on this? I can't offer any specific help, but I was rebuilding my 2nd carpc over the last month to six weeks and I am seeing the same behavior with my unit using the serial ALP1 Sirius adapter (which has been working fine when I plug it into the other carpc).
It does appear to be related to RR, because the behavior is weird, but has some consistency. For example, if I launch RR and go straight to SAT quickly, I always get the MP3 list. If I launch RR and wait for some time, I have a much higher success rate of getting the Sirius channels to list. I shows my signal strength for a few seconds (changing strength) and some of the channel info starts populating, and then it "hangs". I can return to the main menu, but it never works. Unless someone has a better answer, I am going to have to copy the RR folder from my old PC to the new one.
NOTE: Now that I think about it, I did install RR manually on the other PC, and on this one I used the latest installer.......I may look into reinstalling manually as well.