Can you post a screen shot of what the BIOS looks like?

Is there any chance that at some point someone replaced the LCD panel
with a different model?

Pete Zahut wrote:

Thanks Fixer. The problem is still there when looking in the BIOS and even
when running a Linux LiveCD so it's not a Windows driver issue. The problem
is *NOT* there when viewing on an external monitor, so thanks to your
suggestions I'll try a new screen cable first as that's the cheapest )

Thanks mate,

Pete