When I first got MEP14 I had the same problem. When you load the program, go to help and scroll down to activate additional funtions and you will see the prompt for activating MPeg2.
Chances are, the current DEP (data execution prevention) settings in your Windows are somehow conflicting with the MPEG2 handling component of the program. DEP has been linked to many software conflicts and is most likely also the cause of the problem in this case. The solution is to configure the DEP options in Windows in a way that will only apply DEP to Windows' own system components (which is the default setting).
In Windows XP, you can configure DEP as follows: Right-click on "My Computer" and choose "Properties" or go to the Control Panel and double-click "System" to bring up the "System Properties" dialogue. Switch to the "Advanced" tab and click on the "Settings" button in the "Performance" section. Switch to the "Data Execution Prevention" tab in the small dialogue that comes up. Now you have arrived at the dialogue where DEP can be configured. Make sure to choose the option that will enable DEP only for essential Windows programs and services and confirm your settings. Done.
In Windows Vista, go to the Control Panel and proceed as follows: "System and Maintenance" => "System" => choose "Advanced system settings" on the left-hand side and confirm "Allow" for the security prompt that might come up => "Advanced" tab => "Settings..." button in the "Performance" section => "Data Execution Prevention" tab. Choose the option that will enable DEP only for essential Windows programs and services and confirm your settings. You will have to restart your computer.