Thomson Sky HD box?
It's a problem with the box, not the tv. It'll appear on any tv if it's pixel mapping.
Here's a few fixes or workarounds:
1. Change the output resolution from 1080i to Auto. This will mean that the TV does all the scaling for 576p streams, which is almost certainly better than the sky box anyway. Downside is the EPG will be in SD and processed, and can look a bit naff. But I'm more interested in video quality.
2. Menu / Options / Picture. Change the 'Size' option to change the overscan. I found the default setting on any HD channels was out and left a black border.
3. If you don't want to do either of the above and leave the Sky box on 1080i, then you can change the blue bars to black through a bug in the software. If you're not using the SCART signal (e.g. for multiroom), then you can safely change the 'Scart / RF1 Picture Format' to 4:3. Amazingly, this changes the blue to black on the HDMI output.
The lack of curtain on 'ON' is because the Sky box doesn't sync with the TV fast enough, so the TV's already opened the curtains by the time a picture shows. I've tried 'extra blanking' options, but I can't win. So I gave up. I assume it's an HDCP problem.