Hello, I've been developing a simple tool using C# as a windows forms application. Everything was ok, but next time i opened my project i get this error while opening Form2 (or Form1) design view:

The designer could not be shown for this file because none of the classes within it can be designed.
The designer inspected the following classes in the file: 
Form2 --- The base class 'System.Windows.Forms.Form' could not be loaded. Ensure the assembly has been referenced and that all projects have been built.

I can open designer in other projects, but not in that specific one. It happens with both Form1 & Form2 classes, so I guess it has something to do with project preferences, not the actual form`s? Has anyone came across this error?