Hi Peter,
Yes, normally I do not have the option to edit attributes on a virtual root folder. However, after creating a new virtual root and referencing it in a new DMX module instance, I was given the option to edit the attributes of the virtual root, which is when I got a similar error. Later, I was not given that option to edit.
I don't mean to make a big deal out of it, just letting you know, and thought that might be what Kenneth experienced.
Rob Ralston