After installing the SignUp or Uniprint Web Services on my server I can no longer use the WSUS service that was installed on the same machine.
This is a known issue.
SignUp requires Isolation mode when installed using IIS. WSUS requires worker process isolation mode. This is the default setting according to the documentation on WSUS operation (attached)
IIs5IsolationModeEnabled (BOOLEAN) False
The two modes cannot co-exist on the same machine.
You will need to seperate the two services and install WSUS or Signup/Uniprint components on another server.