Hi there

I can think of 3 possible problems here

1. Stuck button on remote control (most likely cause)
2. Remote Control failing
3. IR Port on TV faulty (most unlikely)

Resolutions:

1. Check to see if one of the buttons on the remote control is pushed down or stuck down - especially the power button, as this could be a reason why its not responding properly AND that the TV is going to standby mode AND switching itself on again.
2. Replace the remote control.  The model you require is RM-ED035.  Available on Amazon or 4ourhouse.co.uk
3. IR Port - The most unlikely cause, and the most costly if it is.  You would need to contact an authorised Sony Repair Centre to get this checked out/resolved

 Cheers