First the file name is not BDB_dotnet.sln or BDB_dotnet_vs2010.sln, this is minor but a bit misleading.What is the name of the solution file you are using? The above two solution files exist in the db-5.X.XX/build_windows directory (X.XX being version numbers). They are the solution files you should use for building the C# API.
second, and more importantl,y it appears no native libraries are built to the above mentioned directories. The only one I can get to build is win32\release the rest fail with the linker error Cannot Open Input File 'libdb53d.lib'Which version of Berkeley DB are you using? Which version of Visual Studio are you using? Exactly what steps are you using to build?