Graphics freeze after suspending Ubuntu 10.04

First of all, I'm sorry for my bad english speaking, I'm young yet... but I'm already enjoying Ubuntu!

Everything works really fine on my laptop, except one thing. When I suspend it, it does work perfectly, but when I try to recover my session, the graphics freeze. Then, all I can see is the mouse and a black background.

My laptop is an Acer Aspire 6935g:

Nvidia GeForce 9600M GT (with its own Nvidia driver)
Intel Core 2 Duo P8600
4bg RAM DDR3

I discovered that problem the first time I suspended the 32-bit version of Ubuntu. Now I have the 64-bit version (amd64), but that issue is still present.

I'd love to solve that, because I do use that function every day.

Thanks!