Monitor/projector display looks fuzzy

Hi there

Not sure if I'm posting this in the right section...but here goes.

I'm using an HP Compaq nc8430 laptop. Graphics card according to specs is an ATI Mobility Radeon X1600.
It's the first time I installed Linux for use on my personal laptop and I'm having trouble using it with a projector or a CRT monitor. The display on the projector and monitor behaves as if there is a heavy cellular phone signal interfering with it. It's the only way I can explain what it looks like :o
I have tried changing the frequency and resolution but to no avail. Is this a driver issue? I'm using Mint Release 9 (isodora).
How can I fix this?