I ran the dead pixel test on helath checker and everything ok.

However when I am on a white background (Google homepage for instance) there is a small circle which is lighter than the rest of teh screen.

However this is not noiceable on a black background, only noticeable on the white and other colours.

Is this a dead pixel - no fix?

No, this isn't a dead pixel, but it is a common defect for the N900 screen.

If the "circle" is as large as a pixel, then it could be a dead pixel.

However, if the circle (as I think) is far more larger than a single pixel, your screen has been damaged by something, e.g. umidity (like mine, which has a lighter circle like yours because of some water it took a year ago).

I'm afraid you can't do anything to fix that, sorry!

EDIT: didn't know about that common problem, however I'm pretty sure that my screen was damaged by water; can't guarantee for yours

Thanks for the replies

yes it is around the size of a finger nail - maybe a little smaller - just a bit annoying and once you notice something your eyes tend to focus on it!

I too was unaware it is a known fault

There is a fair sized thread on here devoted to the light spots on the screen and many people have them in the same place. I can't say I know for sure what caused mine, but one is just below where the power button is when the slider is open and I have noticed if I'm not careful pressing the button with the slider open there is colour distortion in that exact spot caused by pressure on the back of the screen, and the other larger one is exactly where my finger hits the screen when I scroll web pages, could be a coincidence though. Some people have speculated they are caused by certain components behind the screen getting hot which would explain why they are often in the same place for different people. I do have a very small barely noticeable spot on my spare N900 as well, but it is in a different place.