You can do a font test to see if you can identify corrupted font(s).

• http://browserspy.dk/fonts-flash.php?detail=1

You can try different default fonts.

• Tools > Options > Content : Fonts & Colors > Advanced
• [ ] "Allow pages to choose their own fonts, instead of my selections above"

You can use this extension to see which fonts are used for selected text.

• fontinfo: https://addons.mozilla.org/firefox/addon/fontinfo/

You can also try to disable hardware acceleration.

• Tools > Options > Advanced > General > Browsing: "Use hardware acceleration when available"

Hey thanks for the reply. Not sure which one of these worked nothing changed until I restarted firefox.

You can try different default fonts.

   Tools > Options > Content : Fonts & Colors > Advanced
   [ ] "Allow pages to choose their own fonts, instead of my selections above" 

You can also try to disable hardware acceleration.

   Tools > Options > Advanced > General > Browsing: "Use hardware acceleration when available" 

But it is back to how it was thank you very much!

Having said that the sized problem is still there and its not for every website, so far google is affected and bbc website as far as i can tell so far. The bold text and font has been corrected but some webpages text is very small. Any ideas?

here are some images. Most web pages are fine it's just some that do this weird resizing in firefox.

EDIT. Just found another website that does this http://www.w3.org/ if there is a relationship between them

i think i have solved it i have increased the default font size which is arial in the options tabs to 16 and the pages are displaying the same as chrome! Is this the default value? But sorry to bother you,

Reset the page zoom on pages that cause problems.

• View > Zoom > Reset (Ctrl+0 (zero); Cmd+0 on Mac)

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