Skipychic, I don't know if this is related to your issue or not, but something you might want to check.  I had a problem with one of my runtimes not loading.  I got an error message stating that it didn't appear to be a runtime folder.  Sure enough, I checked it, and the heirarchy was hosed.  It just had "libraries" as opposed to the higher "runtime" named folder.  Simply fixed by adding a "runtime" folder and moving the "libraries" into it.  Now it loads up fine.