Problem changing enterprise calendar

[Ztypical]

I am following the recommended procedure to change the enterprise calendar:
Select Tools/Enterprise Options/Open Enterprise Global,
<make some changes to the calendar>,
click 'save'.

I get the error message: "The resource global is already checked out to
another user".

I check to see if I have it checked out, and I do, because I opened it in
the procedure. If I either close without saving or force it closed, I can
start again, but I end up in the same place.

My login does have rights to: "Save Enterprise Global"

Any advice?

Thanks in advance,
Michael