MP client fails to play video (1 Viewer)

[baffledboy]

Since i did a fresh install of RC3 my separate client HTPC has developed a seemingly random problem wherein after playing live tv or watching recorded tv it no longer responds to channel changes or starting a new video. The tv server itself seems to be unaffected as I can view different channels/watch recorded tv absolutely fine, but this has happened on two separate client machines. Can anyone throw some light onto the issue?

TV-Server Version: MP1 RC3
MediaPortal Version: MP1 RC3
MediaPortal Skin: Blue3
Windows Version: XP Pro SP3
CPU Type: Pentium Core 2 E2140
HDD: WD 180GB SATA
Memory: 512mb ddr
Motherboard: Asus P5LD2-X/1333
Video Card: Nvidia Geforce 8500gt
Video Card Driver:
Sound Card: ONBOARD
Sound Card AC3: Coaxial out
Sound Card Driver:
1. TV Card: Hauppauge WinTV Nova -PCI
1. TV Card Type: DBV-T
1. TV Card Driver:
2. TV Card: Hauppauge WinTV Nova PCI
2. TV Card Type: DBV-T
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: Nvidia
MPEG2 Audio Codec: Nvidia
h.264 Video Codec:
Satelite/CableTV Provider:
HTPC Case: Ahanix D.Vine 5
Cooling:
Power Supply:
Remote: MCE
TV: Samsung LCD 32"
TV - HTPC Connection: DVI-HDMI