Okay, do this.

On the top of the t.v. itself, hold down the Volume+ (up) and the Menu button down at the same time. This will turn off the "power lock." This is also how you turn on the "power lock." (Though I can't think of a reason anyone would ever want to do this.)

Thanku so much , i had the same problem and i tried it VOL+ and Menu button on TV set and it works...

Please can anyone help done the solution you said holdin down buttons to enable me to unlock but nothin is happening have you any other ideas to help me

I have the same problem with mine. Walk up to your TV, press and hold the power button on the front of the set. While holding this button, press the power button on the remote.

Mine behaves this way on all functions. Even to change the channel, volume or input (among other things) I have to press and hold the power button on the set. Very annoying. I'd be interested in hearing from anyone who might have had this problem and found a solution for it. Viewsonic support isn't qualified to troubleshoot these kinds of technical issues.