bill - 2:47 am on Oct 29, 2011 (gmt 0)
I have many Win7 installs, and none of them have desktop icons that can't be removed or changed. Your situation sounds odd.
It's hard to say where you may have messed things up in the registry. Did you by any chance backup the registry settings before you made changes? If you don't have that, do you have a full image backup of your system? Before I mess with a Windows machine I make sure it's fully backed up so that I have a chance of restoring it to its previous state.
If you don't have backups I'd say a Repair Install would be in order. That may restore some of the original settings.