Can't change accuracy of measurement

When using the evaluate : measure feature, I want to change from 2 decimal accuracy to 4 decimal.  Wether I change the accuracy using the arrows or direct entry, I receive an error that says "Please enter an integer between 2 and 256".  Screen cap attached.  I also receive the same error when attempting to change units from inches to millimeters.

Now what do I do?

SW 2009 SP 5.1

SolidworksParts And Features