If you've ever had to strong name sign the MS Enterprise Library, you'll find that it is a rather difficult task.
Luckily, this link below is a very detailed and complete explanation of how you do it. I followed these instructions exactly and was able to successfully strongly name the entire library.
http://www.mvwood.com/blogs/blog/archive/2006/06/22/Adventures_in_Strong_Names_with_Enterprise_Library.aspx