Vista - Strange Media Center Problem

Afternoon all.

I'm convinced the problem started with Service Pack 2. Never mind not being able to play a video, I'm having a problem stopping them. I have the Media Center ir remote and when a video ends, or when I press stop, you SHOULD see the menu - "Stop, Restart, Resume and Delete" but I don't. When I press stop, the video merely freezes. To get the menu I have to press stop (video freezes), play (video resumes) and then stop a second time to get the menu to quit playback.

At first I thought a codec problem. New codecs, same problem. Tried KL Mega Codec pack and KL x64 codec pack as well as Shark007's VistaCodec packs (including his x64 one) but both with the same problem. New video drivers, new chipset drivers et al - still no change.

So i tried without SP2 - used an old backup from my Windows Home Server to go back in time without the mess of uninstalling a service pack. Worked fine. Installed the newest codecs - still works fine. Installed SP2 again and it broke.

Also, to add insult to injury, I have a couple of HD video clips that are encoded in WMVHD which behave properly - my suspicion leading to the idea that codecs by Mickeysoft that came built into Windows work fine and that addons ones don't.

This problem is just silly as far as I'm concerned and I'm really struggling to find a solution. Anyone got any ideas?

Cheers
-Dave

P.S. - Windows Media Player works fine