Need Help with FSX Switching Sound Devices

Has anyone experienced this:

1. Using FSX with multiplayer (MP), and with Vista OS
2. Using two sound cards; one for playback sounds (call it card a) and one for recording sounds (call it card b).
3. You start FSX and check the Windows Sound Devices in the Sound Settings. For Sounds you see Default Primary Device and for Voice you see Default Primary Device.
4. You know that in the Vista Control Panel Sound Devices window you have the card a set as the default for sounds and card b as default for recording (voices) because you see the green checked icons next to the respective cards.
5. You go into FSX MP and you hear the sounds from the aircraft and the ATC voices from whatever session room you're in both coming from card a (the playback card)
6. So, you go into FSX Sound Settings and change the Sound drop down selction to match your card and not just default primary device. You do the same for the voice.
7. You try MP again and still same problem.
8. Now you shut down FSX and restart it, and then you check FSX Sound settings. This time you see the cards you selected shown in the sounds and voice drop downs. Not default primary device. In other words, after the restart of FSX it keeps the selections you made.
9. Finally FSX MP sounds are coming out card a and voices are coming out card b (which is your headphone and mic). All is good, no more problem.
10. You quit for the night, shut down FSX and the next day you decide to fire up FSX and join MP again. However, the sound settings have changed back to default primary device in both drop downs, and you're right back to step 5.

Now, I have to do this each time I start FSX and want to join multiplayer; I have to make sure the sound devices are selected then restart. My point is, why would FSX keep reverting back to default primary devices instead of keeping what I selceted. In WinXP, I set these settings once when I installed FSX and that was it, but with Vista FSX has a mind of it's own... Oh, does Win7 do anything like this?