Are you using the original 20GB hdd or do you have the 120GB hdd? I don't remember exactly what problem arose for me, but once I got my 120GB hdd Xplorer360 Beta 6 no longer worked correctly for me. I found another copy of Xplorer360 Beta 6 somewhere online in which the guy done something to it to make it work correctly with the 120GB hdd. Not sure if that is why you're having problems, but it very well may be the case, you may need that tweaked version of Xplorer360.
Same thing goes for you if you're using the 120GB hdd. You may also need the tweaked version.
Sorry if that doesn't help either of you, hopefully it will. If not then maybe someone else can be of help.