Unable to start WSuS on SBS 2011

Hi all

I'm unable to start the WSuS Administration website on SBS 2011 (fully patched). If I try to start it manually I get

"The process cannot access the file because it is being used by another process. (Exception from HRESULT: 0x80070020)."

I've checked with netstat and there is nothing using port 8530, and we have no AV on the box. If I change the port on the website from 8530 to 8532 I can start the site successfully, but of course the SBS console doesn't see it etc.

Can anyone suggest a resolution?

Many thanks

Jim