MP not reappearing when I quit external DVD application

[jmbillings]

TV-Server Version:
MediaPortal Version: 0.9.2.19510
MediaPortal Skin: ReVision
Windows Version: Vista HP 32bit
CPU Type: AMD 4450e
HDD:
Memory:
Motherboard:
Video Card:
Video Card Driver:
Sound Card:
Sound Card AC3:
Sound Card Driver:
1. TV Card:
1. TV Card Type:
1. TV Card Driver:
2. TV Card:
2. TV Card Type:
2. TV Card Driver:
3. TV Card:
3. TV Card Type:
3. TV Card Driver:
4. TV Card:
4. TV Card Type:
4. TV Card Driver:
MPEG2 Video Codec:
MPEG2 Audio Codec:
h.264 Video Codec:
Satelite/CableTV Provider:
HTPC Case:
Cooling:
Power Supply:
Remote: Hauppauge 45 button
TV:
TV - HTPC Connection:

I have an odd problem - I am trying out PowerDVD and WinDVD for external playback of DVD's (as I have the black screen / non playing issue within MP otherwise). They launch fine, and I have also got the Hauppauge remote working now (check my blog!) but when I quit the external player, MP never reappears, I just get a black screen. It seems this *is* MP as when I right-clicked with the mouse, I got the top bar, and I could then click the exit button and reload MediaPortal - but I don't want to (have to have the wife) do that every time!

Any ideas?