MSBuild ResolveProjectReferences Error

My MSBuild build script executes fine on all the development machines, but fails to run on the build server, except for the Trunk build. Branches all fail with the following warnings indicating the source of the problem:

Target "ResolveProjectReferences":
    C:\WINDOWS\Microsoft.NET\Framework\v3.5\Microsoft.Common.targets (0,0):  
        warning : The referenced project '..\..\..\Class Library\
            Company.BusinessModel\Company.BusinessModel.csproj' does not exist.

I can't understand why this error is even appearing - I have verified that (relative to the csproj being processed) the referenced project does exist. Copying (file copy) the checked out code to my local machine and running the script, the build completes as expected.

Is there anything obviously wrong here? An开发者_如何学编程ything I can check to try and resolve this mystery?

EDIT:

I've tried running MSBuild against the project raising the build error in isolation, so it's not the rest of the solution which is the problem, just something about this specific .csproj file.

I actually found the problem. It's a bug in Visual Studio 2010 with path names totalling 259

http://support.microsoft.com/kb/2516078

Have you run msbuild in diag mode. That should give you some hints about the current path, and the relative path that MSBuild is trying to search.

msbuild myproj.msbuild /v:diag