RPi some instabilities regarding live tv

Hello there,

I am using my tiny rpi with raspbmc xbmc 12.1 as a frontend of my mediaportal server running win 7 64 bit with mp 1.3.
In this server I've got two s2 tv cards.
In general the whole thing is working quite ok however there are some issues.
-when the system is recording on one card the rpi wont play live tv, at least in 2 out of 3 times
-same goes for one card being busy by another mp client
-I sometimes get an error message saying "pvr client" and the rpi wont play live tv again
-sometimes the rpi blocks a card (even when the rpi is already shut down) causing my server to not got to sleep and to not let my other clients watch tv

I would provide logs if I knew how.
Anyone else having these problems?

Thanks in advance,

Rico