Program does not contain a static 'Main' method suitable for entry - Occasional error

This question has been asked, but none of the answers resolved my problem. I get this error only occasionally, like after opening my solution for the first time. I am using Monodevelop, and开发者_如何学Python compiling with Mono also, under Mono I get no error, and even stranger, after compiling with Mono and switching back to .NET the error disappears.

I have a 'Main' method of course, and tried switching to a 'Class library' output in visual studio which did resolve the error, but that is not the type of project I want, I need my main method and want to be able to run it like a console app. The build action on my files is set to 'Compile' and im not using WPF, so I have no app.xaml file.

I will be running the program as a service, so I am worried this will cause problems of some sort. I assume though, if it builds correctly, that build will be OK?

Any info appreciated.