Multiple references, not updating most recent version

Question

I have built a C# program which consists of one executable project and 7 DLL's which are referenced. I'm having trouble with one DLL which is a user control which is used in the main project. Sometimes when I open the main project I get multiple errors saying, "Could not find type 'UserControls.ucDataInput'. Please make sure that the assembly that contains this type is referenced. If this type is a part of your development project, make sure that the project has been successfully built." Where ucDataInput is the user control. All instances of this control then dissappear. Sometimes I can fix this by re-compiling all the DLL's and then refreshing all references in main project. I also always have warnings when I comile saying, "Warning: The dependency 'DataStorage, Version=1.0.1857.23604, Culture=neutral' in project 'VesselComponent' cannot be copied to the run directory because it would overwrite the reference 'DataStorage, Version=1.0.1875.21789, Culture=neutral'." where DataStorage is another DLL i have created. I fear the problem may be cause because the DLL's reference each other and are also referenced in the main project. There are no circular references tho. So for instance if I have 2 DLL's A and B, A references B and the main project, C, references both A and B. I think what is happening is that unless A and C are recompiled everytime B changes then they are referencing different versions which creates a problem. Is this the problem? and how can I solve it without re-structuring my whole program? Cheers