Resharper 4 builds fails to load in vs 2008 team system developer edition

I have tried several different nightly builds (most recently the release candidate) and they always give me the message, "The Add-in 'JetBrains ReSharper 4' failed to load or caused and exception. Error Message: The system cannot find the file specified." This machine is windows 2003 with VS 2008 Team System Developer edition installed. No other versions of VS are installed, and when I run VS with logging enabled, the only entry for resharper is this:

28 2008/06/04 17:46:11.434 Information Microsoft Visual Studio Loading .NET AddIn: ReSharper ]]>

Any ideas?