Changing System Name

[UncleJoe]

May be it's just my computer, or something I don't know about, but...
In planet view there is a box, lower left, with an option to change the name of the system. When I change it and click the check mark (or hit return, etc.) the system name remains the same as it was before, i.e. ignores my change.

Planet names on the other hand, stay changed when you change them. What's going on?

[Doomshade]

I have only had this happen once and I am pretty sure that time I was using some reserved or invalid characters (I think I tried naming a system V or W or VI something like that).