I’m trying to use PrinterSwitch, but get an error that the PrinterSwitch plug-in cannot be enabled (Windows)

The problem is caused by the security settings of Windows Vista/7/Server 2003/Server 2008.

To correct the settings, do the following:

Navigate to 'Computer'; right click, select 'Properties'.
Now click ‘System Protection’, go to the the 'Advanced' tab, then click the 'Settings' button in the 'Performance' section.
Click the 'Data Execution Prevention' tab. Click the Add... button and add the FileMaker Pro.exe file to the list.
Relaunch FileMaker - the problem should now be fixed.