Please attach a screenshot of the error and post the graphics section from about:support. Everything looks correct to me on my machine.

Hi Thanks for the quick reponse. Screenshot attached (I use dual screen and this has been cropped to just show the Firefox window). Graphics info: Adapter DescriptionATI Mobility Radeon HD 530v Vendor ID1002Device ID9555Adapter RAM512Adapter Driversaticfx32 aticfx32 atiumdag atidxx32 atiumdvaDriver Version8.743.2.0Driver Date6-18-2010Direct2D EnabledtrueDirectWrite Enabledtrue (6.1.7601.17563)ClearType ParametersClearType parameters not foundWebGL RendererGoogle Inc. -- ANGLE -- OpenGL ES 2.0 (ANGLE 0.0.0.686)GPU Accelerated Windows1/1 Direct3D 10

Does the issue still occur if you start Firefox in Safe Mode? http://support.mozilla.com/en-US/kb/Safe+Mode

There is no problem in Firefox safe mode. Firefox 3, IE, Chrome and Safari are also OK. It was from Firefox Safe mode that I diagnosed the problem. Switching off the Add ons didn't help so I tried other options. It was only when I switched off 'hardware acceleration' that the problem went away. When I switch 'hardware acceleration' on and off the problem is also switched on and off.

You can try updating your graphics driver (your current driver is from 2010) and test again.

(I don't currently have a machine with HWA enabled to check if this is just a driver bug or a bug in HWA)

Thanks for your response. I'm using an HP laptop with 'HP Support Assistant' which automatically keeps the system up to date. The littleones.ie website belongs to my client. The problem is that visitors to the Little Ones website may be experiencing this problem - which will be affecting the effectiveness of the site. We can't ask visitors to littleones.ie to update their graphics drivers before browsing the site!! Someone else I have asked to view the site had the same problem so it is not just my PC- I'll get a spec of their system if that would help. Do you know if a website can ask a browser not to use hardware acceleration? I've used Firefox on many websites without this problem. Is their something in the HTML or CSS of littleones.ie which could be upsetting Firefox /HWA?

Seems to be caused by a missing #leftcol { clear:both; }

If I add that CSS rule then it displays fine.
Without it I get the screen as in your screenshot with specific font sizes.

The same happens in other Firefox versions like Firefox 3.6.23 and the latest Nightly build

Many thanks, that seems to have fixed it. Odd though that the error only seems to manifest itself when using Hardware Acceleration and that IE, Chrome etc don't seem to be affected. Thanks also to fmdeveloper for assistance.