Such strokes appear on disk activity with some SATA- or RAID-controllers, and, unfortunately, sometimes unavoidable. This problem caused by that controller transfers data on bus by large packets and doesn't provide time to other PCI-devices. Amount of strokes may be decreased or strokes may be removed by changing PCI DMA burst length or PCI Latency in "Hardware" tab of Behold TV settings. Try to change settings referred to PCI bus, SATA and RAID-controllers in system BIOS or in controller BIOS. Also check, that tuner and SATA (RAID) controller don't share same interrupt (IRQ) line.
Same strokes may also appear on energy saving of concurrent CPUs (Cool'n'Quiet, C1E, Intel SpeedStep), when for economy and heat lowering CPU and system are put into state when stream data transfers over PCI/USB bus can not be safely performed. CPU energy saving may be turned off in BIOS setup of motherboard.