Shark007 said:
Well, even though I enjoyed the pat on the back I have no other advice to offer.
I highly doubt any 'Microsoft' supplied/installed software is causing this issue for you.
If you don't mind, I'll go off topic a second.

In the past, I have used Media Player Classic to get different media format to "play", but now MSFT has delivered more versatility and therefore more formats work "out of the box", such as m4v.

My question to you is do you know of webpage that lists the formats that are still not supported by Win7?

I don't want to ask you to explain to me about codecs, but can you recommend a good source for learning more about them and when to apply them?