Your not the only one having trouble with the digital adapter provided by Time Warner (Cisco). We have spent numerous hours with the techs from TW on the phone and one at our house and still cannot turn on or off the sets with their remotes. Also having other problems with keeping full screen on new HD LG TV and can't change the volume. No solution in site. TW tech last time said "it is what it is". How's that for a solution to the problem. It's not your cheap TV.
As I stated earlier there is a known issue with the remote controlling certain TV's. My advice would be to get a normal Time Warner remote. I have also seen the adapter not holding the stretch setting after it is turned off. Both these issues need to be addressed by Cisco. They can not be fixed on the phone or by a tech in the home.
Or you could use your tv remote to turn on and off and to control the volume in the meantime. I have done it for years - after programming so many remotes over the phone, I didn't want to work on mine after upgrading the tv. Life is too short for tv frustration.