I had the same issue with w7 7260, i simply used windows help to search for RPC and followed the instructions on enabling it. Worked like a charm.
I can't seem to open any folder using Explorer in Windows 7 RC b7100, as it fails with the above error. This happened after Explorer stopped picking up metadata on files, and so I killed and restarted explorer using Task Manager. Files and folders on my Desktop still show up, and files still open in their respective applications, but folders won't show, as with the error. Happens with any local folder.
I can't find anything on Google. I haven't touched any Explorer settings, and I'm not interested in an Explorer alternative. I can restart, but this has happened once before, so I'm thinking it'll happen again after a restart. Anyone have any more permanent ideas?