I am fairly new to HCL and am considering this over Crafty Syntax, but I am really concerned about this issue because I work in a school district that has MANY macs running firefox.

Here may be a fix, PLEASE TRY IT and let me know if it works. . .
File: class/js/aardvark. php
Line 59: <img alt="Aardvark" id="aardvark_img_'+this. object+'" width="0" height="0" src="'+this. url+'" />
Remove: alt="Aardvark"

Also,
File: class/js/normal/aardvark. php
Line: 312 <img alt="Aardvark" id="aardvark_img_'+this. object+'" width="0" height="0" src="'+this. url+'" />
Remove: alt="Aardvark"

From what I could gather it appears the javascript in Firefox on a mac is displaying the ALT tag with the image.   Either remove the tag altogether or replace it with "Live Support" or something that makes sense for your site.

PLEASE LET ME KNOW IF IT WORKS!

Hope it helps,
Chris