Why am I being blocked from formatting borders and shading?

[Common Man]

Only in a particular Word document am I having the following problem:

When I attempt "format borders and shading" (which includes "page border"),
I am blocked from doing so with the following error message:

"The measurement must be between 1 pt and 3 pts."

When I copy the table to a new document, I have no trouble. When I copy
everything in the document to a new document, the problem remains.

 

[macropod]

Hi Common Man,

It may be the document has become corrupt - your problem description certainly suggests this possibility.

You may be able to retrieve the situation by inserting a new, empty, paragraph at the end of the document, then copying everything
except that new paragraph to a new document.