Please download the "CheckDesigner_QBQN_Patch.exe" patch from the link below and run it. Please make sure that the path in the dialog that pops up is pointing to the same folder in which you have your program installed. By default the location is "C:\Program Files\MySoftware\CheckDesigner".
Note: It is also recommended that you upgrade your Check Designer program to the 2007 edition, version 7.
To do so, open your existing version of Check Designer and go to Help and Product Updates.