Whilst watching Deal or No Deal on the 17th June 2009 I noticed that box number 8 which was opened earlier in the program was shown again closed. Does this show the program is fixed or simply cut together in such a way that it is better TV and this is just a continuity error?

If you are in the UK you can see the full show at:
http://www.channel4.com/programmes/deal-or-no-deal/episode-guide/series-2009/episode-144

The part which shows the magic 8 box being opened and then is closed again and then vanishes is at:
http://www.youtube.com/watch?v=IXvwypbXER8

Let me know what you think!

Right, what I think happened is that they do "pick ups" at the end of the recordings of things they are not happy with.

And the second time when the box was shown closed was during one of these "pick ups" when I presume Marios was asked to open his box again.

All down to the editors

Well done to you for picking up on that

Well spotted!

I think Collydolly is probably right. I'd guess that for whatever reason they didn't get a decent or useable shot of Marios opening his box during the game itself, and so after the game they asked him to open it again. Due to the unpredictable nature of proceedings the camera operators have to be constantly on their toes to try and get every shot, but occasionally they might miss one. Sometimes there are other reasons why a shot can't be used too. In those cases, after the game is over certain boxes are set up and opened all over again. There's nothing sinister about it.

Obviously that time though the crew on the floor reset Michelle's box too by mistake.

Yep - they do re-openings after the main show is filmed fairly often