Has anyone out there come across a similar issue to this?

I have a brand new Dell PE R420 server and 20x Wyse E02 Network zero clients.
I have been told by Wyse sales that there is no limit to the number of wyse clients I can assign to this multipoint server, except the Microsoft licensing limit.

I have set-up the Multipoint installation with a pci-e graphics card (AMD Radeon HD 6450) I have installed the graphics drivers and installed the Wyse e02 drivers.
I do not get the driver warning when installing the wyse drivers so I am assuming they are compatible with the graphics card.

I installed 6 stations and tested the graphics, nice and smooth watching a high resolution youtube clip.

When I added a further 5 stations everything went wrong, the screens all went blank.
Under devices in windows the stations were appearing to install then disappearing again.
Basically totally unusable.

I have tried a reboot, a total reinstall several times, I have made sure i'm running the most up to date drivers.

I have even contacted Wyse support who have told me it must be an issue with my machine, but the event log doesn't seem to show anything useful.

If anyone else has any ideas I would love to hear them.

Thanks in advance