As I'm sure you are aware, last week, myself and James put on the first of two Vista: After Hours events, in Leeds. After the event, I had a brief conversation with Simon, from Simple-PC around Media Center in Vista. Simon informed me (I was so tempted to write 'Simon Said' then!) that he was having issues around connecting his Media Center Extender; the Xbox 360, to his Vista Media Center - the problem being that none of his content was present on the Xbox 360.
Off the top of my head, I couldn't think of what it would be, so thought disconnecting and reconnecting the Xbox 360 in the settings menu's of both the Vista Media Center and the 360 dashboard may do the trick, however, I also suggested that he check out if the content is actually being found in the physical Vista Media Center, as, after all, the Xbox 360 is just extending the physical Vista Media Center, so if there's nothing in there, there will be nothing in the Xbox 360 extended Media Center.
I couldn't give a much better response at that stage, as it was quite a strange scenario, but Simon went home and started cracking on it and, emailed me what he found:
"As you suggested I checked whether it was just the extender or in fact the media center itself and indeed it was the media center, on further digging I found that the music library was intact and that .bmp picture files and divx .avi files were also visible! So after 2 or 3 hours searching the deepest corners of the web I found the answer, hence the email at 3.45am!!! (I wasn't going to let it defeat me). The problem occurs on the installation of Nero and its showtime codecs which then remove registry keys for .jpg .jpeg and .wmv and possibly more which I haven't come across, within the HKEY_CLASSES_ROOT directory, luckily I have another machine running vista without Nero and was able to export the keys across and reinstall to the registry, and like magic all my files have reappeared in Media Center."
So some of the files were present, such as the music library and some of the pictures, and also the DivX files, which wouldn't, by default, be playable on the 360 anyway, but it's interesting that Nero remove's registry keys for the other file types mentioned. This is quite a worrying situation, as Nero is very popular, and the typical non-IT savvy user isn't going to be able to figure out what the problem is, and even uninstalling Nero & Showtime would be unlikely to restore the registry settings that have been removed.
So, thanks to Simon for this information - Simon also writes a blog, which you can read here http://www.simple-pc.com/blog/ and, for reference, Simon found the solution to his problem on 'The Green Button' website, which is a community site dedicated to Media Center. The specific answer was found here: http://thegreenbutton.com/forums/thread/155289.aspx
Thanks to Eden for this extra piece of information around Nero installations:
"When you install nero you can deselect the file associations, As nero likes to try to take over everything mp3, jpg's gif' etc. this is what I do and all my default programs open the right files and not Nero."