Join Date: Jun 2002
Location: in my home theatre
the horizontal line is most probably the vertical sync. In PC mode, your TV automatically changes to Native Mode (no overscan) so you start seeing these "junk". When watching regular DVD player, your TV is NOT in Native Mode so there is a slight overscan happening and the "junk" got hidden.
THX, ISF, Control4 Certified Professional; CEDIA Certified Instructor; CEDIA Certified Designer