First, I assume you mean the RDR-HX680.

Sony is usually pretty good about this sort of thing not happening. Are you certain that you don't have the TV's remote in a "DVD" device mode when this happens?

One thing to check - this might be a HDMI CEC issue (Sony calls it "Control for HDMI" in the DVD manual, and "Bravia Sync" for the TV). Which is to say, perhaps the TV is trying to control the DVD via HDMI. You can try disabling this feature on the TV (I'm not exactly sure where, as the online manual for that model is poor), or on the DVD (turn "Control for HDMI" off under HDMI Settings).

In the unlikely event that there actually IS an issue with the remote, you could change the command mode on the Sony DVD to 1 of 3 different codesets. Check your DVD's user manual under "Other Settings - Options" for the "Command Mode" section (page 115-116 in English). However, if you do this, it is possible that the TV's remote will not have matching codes.