This is a Windows error caused by low GDI (Graphic Device Interface) resources. This error can occur when too many programs are open or the open programs are using a large amount of Windows resources. The MediSoft Case window is an example of a particularly large user of Windows resources. The MediSoft Case window uses a large amount of resources because of the number of controls (data fields) in the window. This is not a MediSoft deficiency, but a result of the information necessary in the window.
Close some or all of your open programs and try again!