[hugh]

The Best Buy employee is either extremely stupid or lying.

Having said that, the problem may not be the TV but Mediaroom. Did you use your old TV with Telus for a significant period of time or did you just start using the new tv with Telus?

If not, hook your old tv back up to see if you get the problem.

 

[hugh]

It's pretty difficult to make suggestions when you are unwilling to try the most obvious ones.

Since the problem occurs when other electrical devices are is plugged in, it would suggest an electrical problem. With "6 tv's hooked up to the system (2 LCD, 4 CRT)", you likely are overloaded.

My advice is to consult with an electrician