P5Q Pro and HD4870. Grey screen with mouse

[Mr.Henrique]

Hi everyone.

I managed to install 10.8.2 on my pc.

But after the installation I can't proceed anymore. All I can see is a grey screen with the mouse.

 

My pc is:

Asus P5Q Pro

ATI HD4870

Q6600GO

 

Any ideias?

 

Thanks

 

PS: I used ###### to create the usb.