This is caused by a conflict with some other program running on the computer and in most cases we have found the culprit to be an Epson printer driver.  If you are experiencing this problem and have an Epson printer, you can check whether this is the problem by specifying some other printer as your default printer. In Windows xp you can go directly to 'Printers and Faxes'.  You can specify a generic text only printer driver by adding a new printer from the File menu.  Set it as your default printer and then try to run the Wildcatt program.

If you can run Wildcatt successfully this way, then your printer driver is causing the trouble.  Try downloading an updated printer driver from the manufacturer's web site.