Black screen?!?

[Chesireh]

Hey everyone,
I have been experiencing a problem with WoW.
Like, I start the game, i login, i choose character and then when ur in the game, it goes black and i only have sound. My monitor then goes on a No input screen while my computer is still on D:
yet when i make a new character and enter that one it will work.
I rllly need some help for this. So please help me