Printing some text

Most of our office is now using Microstation XM.  We have one project where we use Microstation font 30.  On most of the computers when we screen plot the font plots right.  On a few of the computers font 30 plots with some of the letters such as the "C" filled in.  I have check all of the settings that I know of and have check the font files loaded including the order of the font files.  All of the computer have the same settings.  Is there a setting that I have missed that would keep the font letters from filling in.  I know there is an issue with some fonts on XM and I have changed these fonts to TT fonts to solve the issue.  But this plotting issue is only on a few computers.