Odd frame drops or audio mutes

[something fishy]

Hi
Using an nVidia 6100AGP with Purevideo DVD decoder (sorry can't remember video driver version) I occasionally have very noticeable frame drops (it looks like 10-15 frames being dropped). This happens no more than 1-2 per hour and at other times video is perfectly smooth.

I am using PAL std def TV (desktop set at 720*576 @ 50Hz) connected using s-video. This is with the Purevideo decoder set to "smarter" decoding and outputting to VMR9 FSE.

If I use reclock I no longer get frame drops but periodically (also about 1-2 per hour) I get audio mutes of about the same duration (0.25-0.5 secs). This is true whether or not I tell reclock to use directsound or waveout. Audio card is a Audiotrak 7.1lt.

It feels like theres some disagreement between the audio and video clocks that is being gracelessly handled (but then why doesn't reclock sort it?).

Does anyone have any suggestions I have:
- A spare ATI x1600xt that I could swap in (is the AVIVO deinterlacing as good?)
- A spare nvidia 6800GT that I can swap in (seems a bit big and hot for a std def PVR)
- An M-Audio revo 7.1 that I could swap in (but I prefer the Audiotrak as it outputs to analog and SP-DIF simultaneously)
- An ancient soundblaster live! card that I could swap in (would only be temporary, this sends SP-DIF to my hi-fi too and I don't want everything resampled to 48k).

My gut feel is that option 1 is most likely to sort it but I'm reluctant to swap parts unnecessarily as this aside the system is rock solid.

Thanks
Eric