Try turning off "Use extra layer of buffer when recording in TS format".
Here are my results of a first night's test. I recorded five 30 minutes shows at 11pm. This is what I am seeing:
-NBC garbled mess, completely unwatchable, just a pure scrambled screen.
-CBS garbled mess, completely unwatchable, just a pure scrambled screen.
-HLN completely clear, no glitches at all.
-CCN completely clear, no glitches at all.
-DXD completely clear, no glitches at all.
What is different about NBC/CBS vs the other three channels:
-BITRATE. Comcast keeps the local network channels at around 6-7GB/hr, while the other cable channels are much lower at around 2GB/hr.
-MPEG2 vs AVC (MPEG4). The two local network channels are MPEG2, the others are AVC.
BTW, I've checked my hard disks... Mobo is SATA II, drive reporting UDMA mode 5, read/write testing 100-120MB/s. That should equate to writing/reading around 50-60 full MPEG2 HD streams simultaneously.