All

I have a Visual Studio 2003 .NET project which was failing to build, on the
grounds that one of the [third party] assemblies (ICSharpCode.SharpZipLib)
was unable to be copied to the bin folder as it would overwrite another
assembly in the build folder with the same name but of a different version.
My first thought was that one of our projects referenced a later version of
this assembly, and that I would need to update our projects and rebuild them
in the right order in order that our assemblies all referenced the same
version of the third party assembly in question.

I could not find any of our projects that referenced any other version, by
doing a full text search of all .csproj files on my machine. I checked the
machine.config, but no information about the assembly in question was in
evidence. I checked the GAC, and the assembly in question was not registered
there. I deleted every bin and obj folder of every project, and rebuilt the
lot. I still had the same error. I searched the whole machine for instances
of the assembly dll, and checked the version of all of them - version 0.6.0
(which is what was being complained about) was not in evidence, only version
0.5.0. There were also a couple of instances of version 0.84.0, but these
were connected ot other applications, and appeared to have no connection to
my projects. I searched the registry for the assembly name, and came up with
nothing.

Eventually, I registered version 0.5.0 in the GAC, and received no more
complaints. This treats the symptom, but I don't know why - nor do I know if
this solves the underlying problem or whether I've merely hidden it. Where
was VS getting the reference to version 0.6.0 from?

Can someone give me any pointers opf what I've missed, so that I can
understand what's going on, and solve the problem conclusively?

Many thanks in advance!