Can't delete Conditional Formatting

[Look_iPadRing.net]

For whatever reason I can't successfully remove (delete) conditional
formatting in the Manage Conditional Formatting window.

No matter whether I hit Remove or Edit then Delete no conditional
formatting rules are ultimately removed. Yes, they do get deleted when I
click Remove but the Ok and Cancel buttons in the lower left hand side
of the window do nothing.  So I have to X out the window.

Any idea what I should do?

Thanks,

Peter