List Box Problem
 

Intermittently I am unable to select an option from a list box.
Clicking on the item only creates a dotted border around it - not the
traditional highlight and select. This happens every now and again
but
frequently enough to be a problem. The List Box has a cell in a
worksheet as its control source. I've noticed if the file is run from
a network drive this problem occurs. It is not appearing on a version
saved on the desktop. Any ideas? Thanks in advance.