I've jsut signed up to the forum after reading this threat jsut so I can post how much help it was.
I had hamachi installed but today I disabled it (or so I'd thought) I had forgotten that it puts virtual hardware on the system which I'd not disabled, as soon as i clicked disable in hardware manager KSP started up instantly, literally as i'd been looking for a solution while waiting for it to load.
Thank you very much for the help.