Annoying Firefox problem

[Dr. McKay]

I'm using Firefox 13.0.1 on OS X.6.8.

Two sites I frequently visit have just updated their site, along with new favicons.
However, although the new favicons are visible in the URL bar, the bookmarks sidebar still shows the old ones. Deleting the bookmarks and recreating them doesn't change anything.
I've even tried removed all cookies relating to those sites and all my history. No avail.
In Safari or Chrome, the new favicons are nicely updated in their respective bookmarks managers.

Anyone have a similar problem ?
Firefox is my favourite browser and I'd like to be able to solve this...

 

[Gregg2]

Go to your Home folder, then Library / Preferences

Drag com.mozilla.firefox.plist to the Desktop (I might not have that file name exactly correct)

Go back into Firefox (this makes a fresh .plist file) and try those sites again.