HELP ME! External display problems

Hey guys,

Hopefully someone here can help me with my weird problem.

I have my 2010 15" MBP connected to a U3011, via this displayport to mini dp adapter:

http://www.amazon.com/Displayport-T...DTKY/ref=sr_1_2?ie=UTF8&qid=1295805806&sr=8-2

and I am using a cheap mini dp cable along with that adapter. Bought it back when I had an imac so I dont remember where I got it from

Anyway, for all intensive purpose the screen works fine. It wakes up from sleep just fine, and it is more than usable.

However I have a weird problem, expose, magnification, mouse over (the arrow turning to a hand) do not work at all. there is also a lag issue, which seems to make it unusable at times.

I thought it might be an external mouse problem, but when the monitor is disconnected the external mouse works fine, so it must have something to do with the external monitor.

Any ideas?

Oh EDIT:

I also tried this cable

http://www.amazon.com/gp/product/B0034X6SCY/ref=oss_product

which did not work at all. The monitor would recognize that something was plugged in and wake up from sleep, but my MBP never detected the display (it would turn blue for a second like it was going to switch over, but then it would just go back to the desktop, and the detect display button found nothing)