Suddenly cannot tune channels 15+

[itsrick]

Area: Media Portal Program
MP Version: MP0.2.0.0 SVN 9539
Skin: BlueTwo
Windows Version: XP SP2
CPU Type: AMD Opteron 144 @ 2.8GHz
Memory: 2x512MB PC3200
Motherboard Chipset: MB:: AsRock SLI32-eSata2; Chipset:: ULi M1697 + M1695
Video Card: EVGA Nvidia 7600 GS
Video Card Driver: Nvidia 91.33
Video Card Resolution: 1280x768
Video Render Type: VMR9
Video Codec Type & Version: Nvidia
Audio Codec Type & Version: ffdshow
TV Card: Sapphire Theatrix (ATi 550)
TV Card Type: hardware
TV Card Driver: 6.14.10.173
Optional Log: I've never spent much time looking at logs, but I believe this is somewhat relevant.

7/22/2006 1:32:27 PM [Info.] Recorder: start watching on card:ATI TV Wonder Elite channel:20 CNN
7/22/2006 1:32:27 PM [Info.] TVCapture: change channel to :20 CNN
7/22/2006 1:32:27 PM [Info.] SinkGraph:TuneChannel() tune to channel:20 country:1 standard:None name:20 CNN
7/22/2006 1:32:27 PM [Info.] Twinhan: check for twinhan driver
7/22/2006 1:32:27 PM [Info.] SinkGraph:TuneChannel() tuningspace:0 country:1 tv standard:None cable:False
7/22/2006 1:32:30 PM [Info.] SinkGraph:TuneChannel() tuned to channel:20 county:1 freq:507.25 MHz. tvformat:NTSC_M signal:NoSignal

Optional References: any reference

Synopsis: Up until this week, I'd been able to tune all channels without any problem. The last time I could tune higher channels was Tuesday night. I tried recording the "Eureka" premiere on Sci-Fi, and the picture looked wavy--like there was analog noise in the picture. Tuned on my TV (on the same cable splitter) there were also waves, so I figured it was a signal problem. I tried to start the recording, MP crashed, and I haven't been able to tune higher than channel 15 since. Any help would be appreciated.