Yes, I see them for IE, but not for Mozilla. I do not use IE on this machine, but I tested for IE.
Yeah, the html editor is finicky. I've never had any problems with it, so I'm not the guy to ask, but you might want to check out this forum http://moodle.org/mod/forum/view.php?f=224 and post your troubles there. That way the folks who have a good background with it will see your post and help
On a slightly different note (and not at all related to your post), if you're looking to add tooltips to your own webpage, and you don't want to get too fancy about it, you can just add alt="text you want to display" to an img tag.
<a href="moodle.com"><img src="whatever.gif" alt="Click here to go to Moodle.org"> moodle.org </a>
to remover the border, add border="0" to the img tag
<a href="moodle.com"><img src="whatever.gif" alt="Click here to go to Moodle.org" border="0">moodle.org</a>