Occasionally certain fonts in your computer's font library will go corrupt. This can cause various system screens or printouts to display incorrectly.
To determine which font has been corrupted or is missing, print out an invoice and compare it to the following Printout Fonts map. This map shows a typical printout with sections of text identified according to the default font used.
Once you've determined which font is corrupt, remove it and re-install. You can also use a third-party font utility to validate all fonts and check for duplicates.
For more details, see these third-party web sites: