Drupal/TinyMCE vs Firefox weirdness

To have WYSIWYG editing in Drupal you have to install either FCKEditor or TinyMCE (htmlarea is, apparantly, no longer supported). Since I've used FCKEditor in the past I started with that. But it seems incredibly slow!

So I tried out TinyMCE insead but found that NONE of the pop-up based features worked under Firefox. They worked fine under Internet Explorer!

I tried disabling all the pop-up blockers under Firefox... no joy 

Thought it might be a more fundamental problem, but according to the main TinyMCE site and notes on the Drupal site it should work.

Just on the off chance I disabled the popup blocker in Norton Internet Security and that fixed it!

This leads to the strange thought that Norton's popup blocker isn't working for IE (remember TinyMCE was working under IE).