I’ve been dealing with this nasty ASP.NET Configuration Error that only happens on my dev machine for several weeks now. Inexplicably, it will think that some random DLL that is part of my project is locked while it is trying to do the aspx compilation. I finally found the solution in the MS Support Database; the solution? Disable the Indexing Service (or exclude the ASP.NET temporary files section). Arg! The problem seems to be when my build copies a copy of a .dll to the temporary files section, it would start to be indexed by the Indexing Service and was locked so that the aspx compilation couldn’t overwrite it.
For those who might think they have this problem, these are the symtoms (and click on the link for the solution):