First.On the machine u have problem starting on. Delete your WOW\INTERFACE and WOW\WTF and WOW\CACHE folders.

Try restart wow. Still not working. Run the Repair tool in the WOW-folder.

Check that you have soundcard drivers installed. And also check that you have DirectX9c or better installed.

Still not working, check WoW website to see that you have met the requirements for what is supported of hardware.

If still not working, try test your system with 3dMarks or something, to check for potential problems, like video not loading, etc.

You can also try start WoW with the launcher after having done the repair of your wow.

Bufe