freitasm: You probably had an ad blocker at some stage. We use a cookie to test it, so you could clear up cookies and see if this goes away.
Nope never and this is on more than one machine.
A quick survey of available machines indicates:
Ubuntu (2 machines x32 and 64 bits) with Chrome and Firefox, all is correct.
Win 7. 2 machines, Chrome always bad, firefox always good.
XP one machine, firefox and chrome both good.
No ad blockers anywhere ever though the XP machine has noscript on firefox.