Do you use the Avast antivirus program? If so, this problem commonly happens when Avast has moved files that MasterCook needs to its Virus Chest. Please search your Virus Chest and restore those files as explained here:
Also, report to Avast that it moved files that MasterCook needs.
Otherwise, it means that the MCReg.ini file has become corrupt or the install is corrupt (one or more DLLs missing).
The MCReg.ini file registers all of the functional elements of the MasterCook application. If deleted, it will be re-created on application startup. A quick way to check if this is the problem:
1) Close the application.
2) Delete MCReg.ini from the 'Program' folder (where the MasterCook.exe lives).
3) Start the application.
If the problem still occurs, you should reinstall MasterCook.