Seems to be problem with installation script.
I installed it remotely(update 1.03 to 1.04 - WIN XP) and e.g. mplayer routine wasn't loaded at all so DVD playing was refused. Also other problems arised.
Then I reinstalled it again 3times and then it fixed itself. After PMS restart, all modules loaded and started working again.
Strange but same I suspected on another system(WIN VISTA) where after start of PMS transcoding options as MEncoder/avisynth-MEncoder/tsMuxeR etc. were lighting orange. PMS didn't load transcoders correctly. But after few restarts of PMS, all loaded and were working again(without any change)
Maybe when system have slower response in time of PMS is starting, then PMS is unable to load all libraries/modules correctly.
When I will catch up again, I will take debug.log