IE strikes again, causing strange CSS behavior.

I haven't seen this one before. And I can't for the life of me figure out what could be causing this.
Take a look at This Page
To see what I'm talking about, you'll need to view it in a good browser first (Mozilla, Netscape, Opera) Then look in IE.
Basically there's an H3 that also serves as a link to my RSS Feed page.
You don't see it in IE unless you actually hover the mouse over it. Even then, if you move the mouse over the menu on the left, the heading disapears again. At first I thought it could be because it was a heading, but on another page a regular link does it too.
I've got two stylesheets, and it does it on both.
Any thoughts or suggestions?
Here's the main stylesheet

I can't recreate it with my IE 5.5, but I can with IE 5. Not quite sure whats going on their though, as I don't have too much time to look into it right now, just thought I'd pass on the version tests I've done.

-D

Thanks,
What's even stranger is it only does it for me with IE 6.
Both 5 and 5.5 seem to display it fine.

Anyone seen this before, or have any ideas?