buttons in IE8 look fuzzy

Hi - we have been using FCKEditor as the HTML editor in our product and have recently upgraded the editor to CKEditor. We are doing some tests and we've had a number of users report "fuzzy buttons" in IE8. I've searched the forum and can't find anything. Has anyone seen this before? My users are using IE8 on either Vista or XP. Note that for another IE8 user on Windows 7, the buttons look fine.

By "fuzzy buttons" - see attachment.



Anyone come across this before?

-- J