IMHO this happened to first gen of blu-ray players and even PS3 first shipments but not anymore, at least other forums and some reviews keep saying that. And my 60GB PS3 never had a single problem with games or blu ray movies, maybe people are not aware of firmware upgrades and that's why they think a product is not working properly.
And FYI buying over the internet doesn't void any warranty as long as you have the receipt, I have bought many things from forums and
ebay and when I have to validate a warranty I've been able to do so even when the receipt was from another state, however my only experiences have been with Target and Wal-Mart without any problems.
Just my 0.02