Since it's impossible to predict what the graphics adapter and its driver will produce when hardware acceleration is present (especially on legacy systems), it is always recommended to provide also the ability to start your application without hardware acceleration. This cannot be done at runtime as you'd need to destroy the ViewportLayout control and recreate it on the fly.
Restarting your application without hardware acceleration allows the user to calm down and start working with consistent 3D graphics even if performances are worse.
The best approach would be to save a flag in the registry, quit then reload your application with ViewportLayout.AskForHardwareAcceleration = true/false depending on the user settings.
To help your customer you should generally proceed as follows:
In case this wouldn't solve the issue, a graphics adapter upgrade will be necessary.