Post \ HTML format – can’t get colored text

I installed WP 2.5 with an automated setup my ISP offered on my server, and manually upgraded to 2.6.1. I’m playing around with plugins, themes, etc., and getting to know the product. So I’m using TinyMCE, Advanced TinyMCE plugin, etc. and trying to write posts with the visual editor, but much of the formatting for pictures or even colored text seems to disappear, and when I view the post, I get plain text. My initial editor code seems to look like this:

<p>THIS IS BLACK TEXT</p>
<p><span style=”color: #ff0000;”>THIS IS RED TEXT</span></p>

but as soon as I save it, it changes to:

<p>THIS IS BLACK TEXT</p>
<p><span style=\”color: #ff0000;\”>THIS IS RED TEXT</span></p>

And the resulting page does not display red. I think this is also affecting the image tag and preventing images from showing.

Is there something I’ve missed in the config? I can’t believe basic WYSIWYG editing does not work…

Thanks for any comments!