I redid the uninstall, reboot, reinstall routine and did not install the Blade skin. That allows me to consistently open MC, but I'm getting either Media Core errors or MC simply disappearing with no error with just about everything I try to do.
I posted this in the bugs post for build .274.
This I can consistently reproduce -- when I open MC, there are a bunch of files that have no listed filename. When I click on one of them and choose "Locate - on disk (inside MC)" it takes me to C: on the directory tree. I click on M: (the network drive where my music & images are), it says "gathering info and updating view" for a few seconds, then it disappears. And I can confirm via Windows Task Manager that it is no longer running.
Also, when I try to sync with my Creative Muvo N200 -- both via Autosync and with that turned off, when I click on the Muvo N200 under Devices, it tries "Retrieving file info" for a few seconds, then gives the Media Core error:
AppName: media center.exe AppVer: 11.0.274.0 ModName: ntdll.dll
ModVer: 5.1.2600.2180 Offset: 00011f6c
I can see this drive in Windows Explorer just fine.