@nobrakes - No I don't know what the culprit cab is but someone else had the same problem and that was the fix. The important thing to remember is that you are able to pre-build in all the good stuff from the extrom by checking that box in the buildos app. That means that your real extrom (stock or custom) is no longer needed and can actually cause problems due to old files or reg entries (designed for a much older version of Windows Mobile than this one is).
It's sort of akin to installing old Windows 98 drivers for your printer under Windows Vista which has newer drivers built in. Sort of a half-ass analogy but hopefully it makes a little sense.