попробовал для смеху с mono запустить

** (<unknown>:14076): WARNING **: Missing member .ctor in type MainMenu, assembly /opt/mono-1.1.13.2/lib/mono/gac/System.Windows.Forms/2.0.0.0__b77a5c561934e089/System.Windows.Forms.dll

Unhandled Exception: System.MissingMethodException: Method not found: 'System.Windows.Forms.MainMenu..ctor'.
in <0x00000> <unknown method>
in <0x0002e> ZXMAK.FormMain:.ctor ()
in (wrapper remoting-invoke-with-check) ZXMAK.FormMain:.ctor ()
in <0x0003a> ZXMAK.Program:Main (System.String[] args)