This happens only with Firefox.
I have several editor panels on the one page and they appear to generate continuously the lines
'CSS Class Paragraph Default Font Size'
'CSS Class Paragraph Default Font Size'
'CSS Class Paragraph Default Font Size'
'CSS Class Paragraph Default Font Size'
'CSS Class Paragraph Default Font Size'
There is a constant flick and a new line appears. This is happening on a PC running XP and Firefox 3.6.13
It does not happen on my other machine which is Windows 7.
Any idea what it could be. The lines seems to drop down from the icons of the toolbar as if they are the 'alt' tags of the icon images.