I've tended to see this when the agent hasn't fully settled after an install. Often a reboot fo a device that has been upgraded resolves it. Failing that try a re-install of the agent and reboot. Do this with the mirror driver enabled or disabled (in the agent config, not just as an option in the RC console.
If you are on 9.5 you may find that HTML works where the classic version doesn't.
Failing all of these, try a different graphics driver version on the remote device.
Failing that get it logged with LANDesk Support.
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