This appears - from the Web page though not the about box nor flagged in the update toast prompt to be the release candidate; I imagine it redoes the nifty Explorer integration (want to listen to a track that you spot while browsing Explorer? easy! want to listen to another track afterwards without sitting around with the Explorer window open? choose Queue-It-Up which is easier to use than spell) and that's why it needs to have all Explorer windows closed, which it did ask for (so why not mention the reboot earlier? I think all installs should say upfront if they're going to reboot).
And when I launch the player this morning it wants to select its settings all over - treating the RC as a fresh install again. Fairy snuff, but the real grrrr-inducing part is when it tells me it seems this is the first time I've used Media Player and would I like to scan my PC for music. What about the substantial media library I already had, with tracks rated and auto playlists set up and my own playlists? The tracks and the physical playlists get found but yes, all the ratings are gone. The dangers of beta I know, but excessively grrr-making.
And why does it say it's going to skip previously deleted tracks if a. it doesn't know about old tracks so b. it doesn't? grrr again
And looking into this has made me a tad curious to boot (no, I know I started out curious, it's all the cats). The recent furore over copy-protected CDs that have the CD label on and hence should be Red Book standard has caused some fairly snotty replies from the RIAA ('get used to it, pirate', is the essence of it). So when the HighMAT feature is described as "creating a standard way for PCs to structure digital media on physical formats and for consumer electronics devices to read these discs" which sounds like CD Audio for multiple formats with menus that work on a DVD player and your car CD player, I wonder if that means it's going to be a really handy idea CD Audio for multiple formats with built-in DRM ?