I didn't run the loader.exe I just deleted the vendor file then opened BB desktop manager and once I plugged my BB in it asked to update to 5.0, did you try loading this way?
I was also able to do a BES reactivation and all went smooth as well with 5.0 loaded, I didn't notice the 3G in the corner just regular 1XEV. so far 2010 is looking great with the new software....