In general, font problems can be traced to either corrupt system resources
or to a corrupt application. Here is a short troubleshooting procedure you
can try to determine which of the two it may be:
Start up the computer with a known good System Tools or Disk Tools startup
diskette (one which contains a complete System Folder). This effectively
eliminates any conflicts you may be having with system extensions or
control panels in your main System Folder. If this solves your problem,
then go back to your main System Folder and move all items that did not
come with the original system software to another temporary folder, moving
one item back in at a time until you diagnose which caused the conflict.
One other possible problem is duplicate System Folders. Your Macintosh may
be "switching" to another System on your hard disk and you aren't aware of
it. You think you're modifying and testing one System Folder, but your
Macintosh is actually using the other System.
Use the Find File desk accessory (or System 7's Find command) to search for
multiple System Folders. If you find more than one, trash all but the
active System Folder. If that remaining System Folder is still a problem,
then move any items from it you want saved to a holding folder and drag the
remainder of the System Folder to the trash. Then start up from an
Installer disk and reinstall the system.