Hi Peter,
You are using the pre-compiled deployment files which are intended for production deployment and not really intended for use in VS.
After the innitial release of version 2.3.8.1 several bug reports came in and these bugs were fixed and the release was patched by updating only the changed dlls. That is why there may be some version differences but it doe snot affect production deployments.
Possibly you could solve it by changing your dll references in VS to "Specific Version" = false in the reference properties.
But in general I recommend for people doing custom development to work with the source code rather than the pre-compiled deployment packages.
See also:
Hope that helps,
Joe