Horizontal White Lines

A strange phenomena has befallen on my Toshiba DLP HD tv and I can't quite figure out what's causing it. 

When watching pretty much any channel, either local or something they are retransmitting (HBO, ESPN, etc) I occasionally see a very thin - one line horizontal white line that appears for a brief second. It will reappear near the lower third of the screen as well.

My though was a funky HDMI cable from the IRD to the TV, but I'm not a believer in paying $200 for a "superior" HDMI cable when the $20 version does pretty much the same thing.

Thoughts?