ActiveX controls or custom controls disappaer in the project!

I have a VB.NET solution with some projects.
One project is the main application, the other projects are custom
controls library.
In the main application I have an ActiveX charting tool.

Sometimes when I open o rebuild my solution I see that the activeX
controls or my .NET custom control are not anymore in the form where I
placed them. They are still the region code:

#Region " Windows Form Designer generated code "

but I cannot use them anymore.

The only way is to set again the reference to the control with "add
reference", remove the old piece of code in #Region " Windows Form
Designer generated code ", and finally pace the controls again.
Of course I have to set all thy property again.

Any suggestion?

Thank you.