As previous post, .net framework v4 has been installed and simdash was unzipped to a new folder (ie I'm not trying to run it from inside the zip folder)
I tried deleting, re-downloading, unzipped into new folder again and re-ran but have the same outcome.
My original simdash and the NFS Shift 2 beta work fine.
I'll have another play when I get in but not sure what else I can try apart from deleting and installing again. I'll also try re-installing .net framework and see if that helps. Will post again if I get any joy.