Tv stops several times on scrambled channels (1 Viewer)

[mantaraya]

TV-Server Version: 1.0
MediaPortal Version: 1.0.
MediaPortal Skin: Blue3
Windows Version: Windows XP SP2
CPU Type: AMD 3500+ (2.2Ghz)
HDD: Maxtor 500Gb
Memory: 1 Gb ddrII
Motherboard: Asrock
Video Card: XFX GeForce 7100 GS
Video Card Driver: 6.14.10.9424
Sound Card: onboard realtek high defenition
Sound Card AC3: no AC3
Sound Card Driver: 5.10.0.5247
1. TV Card: Twinhan 878
1. TV Card Type: DVB-S
1. TV Card Driver: 1.2.3.8
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: MPV CODEC
MPEG2 Audio Codec: MPA CODEC
h.264 Video Codec:
Satelite/CableTV Provider: Astra 19.2 E
HTPC Case: Enlight
Cooling: CoolMaster
Power Supply: Enlight
Remote: Ms MCE
TV:
TV - HTPC Connection:


I have the following problem.
If I watch tv on a scramble channel my picture freezes from time to time. I do not have this problem on fta channels. The effect is the as you would have removed the subscripton card.
My cam is a Matrix reborn but I've also tried an Astoncrypt duo.
In the attached log. The systems had been freezing the picture a 20.45
20.50
20.57

Any help appreciated.