old

try a can of compressed air from a pc shop?

Do you mean in the corners? You might have to take it apart for that. If you're using an SL, it isn't that difficult. I just got done taking mine apart again. It's sitting here in pieces.

If it's just on the screen I'd consider replacing the screen protector. You are using a screen protector, aren't you?

What model is it?

thought so. Got the same problem on my old 5500. The dust seems to come in through the CF slot. if the dust is stuck to the underside of the front glass then you might get it off by using an antistatic spray onto the front such as astapol and then try putting a hoover over the CF port...got to be worth a try before taking the thing apart Id also get a full case for your Z so its not picking up more pocket fluff in the mean time....

Yup looks similar. Antistatic spray is what you use to clean computer screens and or any equipment that gathers dust by electrostatic attraction that is dust jumps to the surface from any passing object and or out of the air. The spray helps to stop this and diisopaits any static charge on the surface which then makes the dust less "sticky". It should work on the outside of the screen even though the dust is inside and might be enough to loosen the dust so a vacume will pull the dust out. I've used this method with laptops before.

Usualy a dead pixel will only be dead in one colour. Use a couple of images over the affected area to see if its this. Antistatic spray should be available in Maplin, Tandy(Radio Shack if in the US) and some HiFi type shops. TV / PC service engineers might have some kicking arrount too. www.cpc.co.uk was where I used to get mine from when I wuz a PC service engineer.

Is it still white when the Z is turned off? If so its dust.