Because VS 2005 seems much slower compare with VS 2003, I was very excited when read a tip , that suggested to uncheck libraries from Configuration Manager. And it really improves the speed of start up.( I don't understand why dependency check became so slow in VS 2005)
I have DotNetNuke web site project and a few library projects, both DotNetNuke and my own.
The problem happened when I changed the code in one of the libraries. It was quite obvious that I had to re-build the library which I've changed.
But the web application still used the old code. After investigation I undestood that it is required to re-build all libraries in depedencies path.
For example, your Web project depends on libraries A,B,C and D, and also C depends on B and B depends on A.
If you made changes in A, you must rebuild libraries A,B,C for changes take affect.