Thanks! Have you tried to remove the references to the categories from this file to see if they can be removed?
Also, I have moved some programs around using the codes you provided, thanks for that. However, it looks like programs that are created with PSLight somehow ignore their PARAM.SFO files, because no matter what changes I make (e.g. changes to name, category) they don't take. Any ideas on that?
Edit: Never mind, the changes to the SFO won't show in the XMB until the next time the app is launched.