MPEG2 InterVideo codecs, that used in Behold TV application for recording in MPEG and Timeshift function, developed to work with sound cards. This means that for sound encoding this codec prefers to work with long audio samples (0.5sec), which by default provided by all sound cards. When recording sound by tuner the length of audio samples does not exceed 40ms that on some rare circumstances may cause falts in codec work. If you encountered such problems, in Timeshift settings and on software encoding in MPEG format you should turn off sound recording via PCI and not generate short audio samples. The capturing of audio stream will be performed by sound card, that's why tuner must be connected to sound card by internal or external audio cable.
Also this may occur on motherboards built on nVidia nForce2 chipset, when "FSB Spread Spectrum" BIOS option is turned on. Turning off this function solves the problem with InterVideo codec. On most BIOSes this option may be found on section "Advanced Chipset Features".