Check for updated video drivers. If whoever fix the computer needed to reinstall or replace the video card, they may have just used whatever they had handy or was on the driver CD.
Check the troubleshooting section of the readme file. IIRC there are a couple similar graphical glitches described there that can be avoided by checking the 'use alphabit' option in the configuration program.
Troubleshooting Tips (& manual install procedure)
