Favicon Issue

Hi all, I’ve got a problem with my favicon that is driving me crazy. I was experimenting with different favicon images earlier today and after eventually creating a nice one, I find that it displays fine on my website http://www.razorpig.com, but the bookmark for my admin login page displays a lower resolution one that I tried previously. The difference is subtle, but if you experience the same problem and look closely, the favicon for the admin login is much more pixellated. I’m using OS X Mountain Lion and Safari 6.1.1. I’ve tried clearing the cache on both the WordPress installation and in Safari – after trying several favicon plugins earlier I cleared all .ico and .png files from the server so there is now just one .ico in the root folder. But STILL it somehow finds two versions – one high res and one low res. On Windows 7 using Chrome the favicon is fine for the actual website but shows nothing at all for the admin login page :-/ My brain hurts. I’ve been on this for hours! I’d be so grateful for any help. Many thanks in advance.