I've owned my 770 since late 2002 and have had ZERO issues. The 770 in this system is virtually never turned off, runs 24/7 except on rare occasions. A quick conservative estimate has my 770 at around 70,000 hours and going strong.
Thinking back the 770 has outlasted a processor, 2 DVD players, 2 cable boxes, 1 TV and a CD player.