Why does my Macbook Pro Crash when I tether with USb cable from iphone 4?

Ok so I pay for the tethering thing for my iphone 4. And when i use bluetooth or wifi it works just fine. But when i connect my iphone to my macbook pro with the usb cable it completely crashes. Like the screen gets gray but sti see thru and it says to turn off my laptop by holding down the power button. and it has it on many languages. Whats up??? what can i do?

I have the MacBook Pro.15 in 2.2 ghz i7 4 gb ram, the high end 15 inch stardard the only diff is that it has hi res anti glare screen.

Plese guys if you have experiene this let me know what i can do.