On the moneysupermarket site, the top row of navigation buttons are drawn using background images. If the images are missing, then the buttons are invisible.

You can block images from a site using a Firefox feature, or using an add-on (e.g., an ad blocker), or using external security software. This article has a run down on some of the most common issues:

Images or animations do not show | Troubleshooting | Firefox Help

The fact that it also affects IE makes me wonder whether a Windows display or accessibility setting might be involved. This article describes the effect of some of these settings:

Accessibility | How to | Firefox Help

Any luck?

Incredible. I only posted the question 5 minutes ago and now a reply. Incredible! You may well be right when you suggest accessibility. I did make some changes because of poor eyesight (as suggested on the BBC website), but is there an easy way to undo them, ie revert to default? I will follow up your Accessibility link. I used AVG and ZoneAlarm for many years, but recently changed to Avasti (still with ZoneAlarm) because AVG seemed to be causing computer lock-ups.

Thank you for taking the trouble to reply to my question.

If you checked the box to override the web site's colors and styles, that could be the problem. A better approach is to use Firefox's zoom feature. You can zoom up the page to have larger text and images, and this will be remembered on a site-by-site basis. To set the baseline to a higher zoom level for all sites, you can use one of these add-ons:

• NoSquint
• Default FullZoom Level

I haven't tried them, but see them recommended frequently. Good luck!

Thanks once again. I normally only use Firefox, so any alterations to Firefox (which I can't recall making) wouldn't be an explanation, since Internet Explorer (not normally used) has the same fault. Thanks again.

See also (High Contast in Windows):

• http://kb.mozillazine.org/Website_colors_are_wrong

Thank you for all your suggestions. The problem is now solved (after 4 months of frustration). I'm using XP. Control Panel / Accessibility Options / Display / Untick High Contrast. Your early suggestion of an Accessibility problem was spot on. Thanks.