Thanks Joshatdot! My last update went fine without performing a clean install, that's why i didn't tried that.
The following was enough for running XBE's again:
- delete all files in E:\CACHE
- delete all files in E:\UDATA\0face008
- delete all files in E:\TDATA\0face008
- Turn off Xbox and power it on again
What i did with the /Userdata:
I copied back my thumbnails of my music. Getting those again from AllMusic...No Way! But XBMC nicely added them to my music... so no problem at all. Setting back my personal settings only took me a few minutes.
I love this version, though i was wondering if its possible to add an 'wraplist view' to programs that works with wide icons... The finishing touch for XBMC

Um. It won't let me edit my retardedly misquoted post. I meant to choose this one. This didn't clear up the .xbe problem. Hope there's a new release soon.