I have a Toshiba SD-3107 DVD player (Region 1) purchased new many years ago when they first came out. It's never given me any problems. However, recently I tried to play the Warner Home Video Doctor Who Key to Time set. Each of the six discs acted the same way. The animated WB and BBC logos would start at the beginning of the disc and then nothing. The disc would not go to the menu by itself or by any command via the remote control. Eventually, after a few seconds of a black screen, the player gave the "Please Check Disc" error message. These discs are Region 1, NTSC, purchased new at a Suncoast Pictures store. Every disc looked clean and unscratched. (Though I did clean the player lens and one of the discs to make sure that wasn't the problem.) When I took the set back, they took one disc out, and it played just fine in the store's DVD player. I have had no trouble playing any of WB's other Doctor Who DVD releases, both before and after trying to play the Key to Time set. That includes Doctor Who DVD releases put out after the Key to Time series. Is there some subtle difference in the recording format of the Key to Time DVDs that trips my machine up, something akin to it not being able to play DVD-Rs? Or was there a bad batch of discs put out? Of course, I'm looking for a solution so I can actually watch the discs rather than sell them off or buy another player.