#3749 Threshhold popup not working in Firefox

[WGrother]

I am running Firefox/1.5.0.6 on Windows XP SP 2 and
when I go into any story, the Threshhold Box that
normally pops up is not displaying, nor can I click on
a comment and get it to unfold to read. THis is
strange, as it works in IE6, and also works in
Firefox/1.5.0.6 on WIndows 2000. I have the following
error message from the JavaScipt console:

Error: $ is not defined
Source File:
http://images.slashdot.org/comments.js?T_2_5_0_121
Line: 580

Which leads to:

$('gods').className='thor';

[Jamie McCarthy]

Logged In: YES
user_id=3889

Transient js loading error maybe?

[Chris Nandor]

Logged In: YES
user_id=3660

Maybe you have a conflicting FF extension? Either that, or maybe you're not
getting all our JS files loaded (I think that part relies on prototype.js) ... try force
reloading the whole page?