This problem relates to ActiveBar AB2DLL.DLL that is used in the report designer
there are several reasons and solutions:
1) Make sure AB2DLL.DLL is placed in the same directory as the other
ActiveReports DLLs. If AB2DLL.DLL is absent, you need to reinstall Active Reports 2.0
2) AB2DLL.DLL creates temporary files with .TB extension. If temporary file was corrupted for some reason, the project with report can throw exception in Visual Studio.
In this case, it’s enough to remove all .TB files from folder with ActiveReports DLLs.