I must have thousands of posts in here. Having so many problems at the moment

We have 3 identical art suites.
All made with the same image running OS X Leopard 10.5.6 on all machines and OS X Server 10.5.6 on our XServe.

One of these machines works perfectly no matter, as long as its allowed.

Two of the machines seem to almost argue about who's going to be able to run the HP scanning software. If I allow it on one of the machines, the second of the two won't be allowed to run it. If I allow it on the second of the two machines, the first won't be able to run the software.

I add permissions to Workgroup Manager by running connecting to Workgroup Manager from the client machine through the Server Admin package. Then drag and drop the application into the User Groups Preferences on Workgroup Manager.

I've tried not signing the software. I've tried updating the software. I'm not sure what else to try now.

It's the fact the third of these three machines works, no matter which of the other two machines I add the HP software on, which confuses me and makes me think it not to do with versions of the software.