That image works fine for me.

Does that also happen in Tools > Page Info > Media ?

<img src="http://files.petapixel.com/assets/uploads/2012/08/star_ratings.png" alt="Why Five Star Ratings Arent Very Helpful When Buying Camera Gear Online star ratings" title="star_ratings" class="aligncenter size-full wp-image-71224" width="299" height="310">

Clear the cache and the cookies from sites that cause problems.

"Clear the Cache":

• Tools > Options > Advanced > Network > Cached Web Content: "Clear Now"

"Remove Cookies" from sites causing problems:

• Tools > Options > Privacy > Cookies: "Show Cookies"

See also;

• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

Try to rename (or delete) the content-prefs.sqlite file in the Firefox Profile Folder.

• http://kb.mozillazine.org/Profile_folder_-_Firefox

You can use this button to go to the Firefox profile folder:

• Help > Troubleshooting Information > Profile Directory: Show Folder

Thanks for your reply cor-el. To respond to your question/points in order:

• the faulty rendering also happens in Tools > Page Info > Media
• I've cleared the cache - problem still occurs
• I've removed cookies - problem still occurs
• I restarted in safe mode - problem still occurs
• I deleted the content-prefs.sqlite file and restarted - problem still occurs

Since posting the problem I've tried various other png files (on disk and websites) and they seem to be rendering OK. I've also visited http://xkcd.com/ (the source of the problematic image) and find quite a few of their cartoons are showing the same problem - so it seems to be limited to particular png images. All images that Firefox is rendering incorrectly are fine when I open them in other apps.

Regards

Jim

Does such an image also look OK if you save it from Firefox and open it in another program (browser) and do images saved via another browser look wrong when opened in Firefox?

Create a new profile as a test to check if your current profile is causing the problems.

See "Basic Troubleshooting: Make a new profile":

• https://support.mozilla.org/kb/Basic+Troubleshooting#w_8-make-a-new-profile

There may be extensions and plugins installed by default in a new profile, so check that in "Tools > Add-ons > Extensions & Plugins" in case there are still problems.

If the new profile works then you can transfer some files from the old profile to that new profile, but be careful not to copy corrupted files.

See:

• http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox

Thanks for getting back to me. I tried saving the png image from Firefox and opening it in another app and it was fine. I wondered if the problem might be my graphics driver (last updated 3 months ago) and tried uninstalling it - the problem disappeared. After re-installing the same driver, the problem returned. I then tried installing the latest driver from the AMD website and the problem disappeared again. So it seems likely that the problem was caused by a bug in my graphics driver.

Your help in getting to the bottom of this is much appreciated - thank-you.

Jim

Update on the above - 1 day later and the problem has returned. I thought the graphics driver update was a solution but I was mistaken. Over the w/e I'll try a new profile as cor-el suggests and see if this clears it.

Jim

Are there settings in the graphics display driver that might effect images?

Nothing that I can think of - my graphics driver is a default installation of the AMD software (though I don't install the Catalyst Control Center). I do a bit of photography and have gfx.color_management.mode set to 1. However I followed your advice and created a new profile and the problem disappeared. Switching back to my original profile and the problem returns. This behaviour has persisted through several reboots so, fingers crossed, the problem looks like a corrupted profile. But I'll give it a few days this time before marking the problem as solved.

Thanks again for your help.

Jim

Did you try to reset the preferences by renaming the prefs.js file to prefs.js.old?

• http://kb.mozillazine.org/Resetting_preferences
• https://support.mozilla.org/kb/Resetting+preferences

You can use this button to go to the Firefox profile folder:

• Help > Troubleshooting Information > Profile Directory: Show Folder

cor-el, I'm using a completely new profile - I imported only the bookmarks from my original profile so preferences started off as default. Also as problem has not returned, I've marked this one as solved.

Best wishes

Jim

You're welcome