Readiness Check Exchange 2013 fails: All Exchange 2010 servers in the organization must have Exchange 2010 Service Pack 3 or later installed

Hi,

I'm installing Exchange 2013 on a new server (Windows 2012) with AD on it (transferred from an old server). The remnants of AD from the old server have been removed, and the server completely removed from the network. However, when I try to install Exchange 2013 on the new box (not transferring mailboxes etc...fresh install), I get the following error during Readiness Checks:

There doesn't seem to be any further connection to the old box (Win 2008 R2 with Exchange 2010). All references were deleted in AD, and the box is switched off. 

Any ideas how I can check if a piece of the old server exists or how to get around this?  I've looked through all the folders in the AD Sites & Services, ADSI Edit, and AD Users & Computers.

Thanks,

Rob