100% CPU at 30 second intervals, *not* My TV specific

[malachy]

Area: Media Portal Program
Windows Version: Windows XP Pro w/SP2
CPU Type: AMD Semperon 64 2800+ (Palermo core)
Memory: 1 GB (2 x 512 MB DDR2700, Xerox chips [probably Corsair, but I don't remember])
Motherboard Chipset: Asus K8N-E Deluxe
Video Card: NVidia GeForce FX 5200 Ultra
Video Card Driver: 78.01
Video Render Type: VMR9
Video Codec Type & Version: NVidia PureVideo 1.02 & Mpg2Dec 1.0
Audio Codec Type & Version: FFDSHOW 20050303 and 20050920
TV Card: Hauppauge PVR-250
TV Card Type: hardware
TV Card Driver: 1.18.21.22266
Satelite/CableTV Provider: Adelphia (SoCal)

error description:
1. Start Media Portal.
2. After approximately thirty (30) seconds, Media Portal CPU utilization jumps to 100% (100 percent) for about two seconds, after which it returns to normal for another thirty (30) seconds. Cycle repeats ad infinitum.

The CPU spike occurs in all modules. When video is playing, either in My Video or My TV and using any decoder, video temporarily slows and/or freezes while audio continues, and then video resumes its normal pace.

No errors listed in the event log. Media Portal logs look clean to my untrained eye, but I have attached them anyway, just in case.

attachments:
capture.log
MediaPortal.log
recorder.log