This error could be caused by a file corruption, registry errors, etc. I would recommend you open the application to create a backup of the database. You can do this with the help of backup features already available within the application. Go to File > Save As or File > Export to generate a copy of the files. After this, re-install the application, but make sure to remove it first with its uninstaller (recommended through Uninstall a program in Control Panel).
If you require additional help, go to Help > About and contact the developer if it's still possible.
Contact info: http://na.sage.com/us/about-us/contact-us