Thankyou so much. That pointed me in the right direction.
On the server in the config folder there is a config file called acls.cnf.
This holds the configuration information for the ACL membership.
I was able to replace this file with the version from another server and all is working again.
Thankyou again,
You have saved me from much pain!
#webMethods#Integration-Server-and-ESB#webMethods-General