Windows Version: Windows XP SP2
CPU Type: Pentium 4
Memory: 1GB PC3200
Motherboard: Asus P4PE800 Deluxe
Motherboard Chipset: i865PE
Motherboard Bios:
Video Card: Gigabyte 6600GT
Video Card Driver: 83.60
Sound Card: Onboard
Sound Card AC3: Optical Out
Sound Card Driver:
1. TV Card: Vbox DTA-150
1. TV Card Type: ATSC
1. TV Card Driver: BDA
2. TV Card: Fusion 5 Lite
2. TV Card Type: ATSC
2. TV Card Driver: BDA
Video Codec: NVidia Purevideo
Audio Codec: Mpeg/AC3/DD.../Nvidia Audio Decoder
Satelite/CableTV Provider: OTA
HTPC Case: Silverstone LC03V
Power Supply: Silvertsone Strider 400w
Remote: MCE USA
TV: Philips 30PW8520 (30" Widescreen CRT)
TV - HTPC Connection: Component

Using the 4-13-06 SVN Build, I have duplicated the original poster's issue. On my setup, all TV channels have AC3 sound.

Start MyTV, enable timeshifting and watch it for a while. The audio progressively becomes out of sync. Rewinding a bit into the TS buffer fixes the issue.

Also, when viewing TV without TS on, after a time, the audio begins to to go crazy. The signal drops in and out, My audio receiver indicates that it is intermittently getting a signal. I have to completely stop myTV in order to resolve the issue.

I've attached logs, but they really don't seem to show anything amiss, as far as I can tell.