Here's an odd one…
I ran a VM with a vanilla install of XPsp2 and IE7 to do some testing to find that unwanted header text appears above the top-right menu ("Skip to main content") 
and the left menu ("Quick Launch").
This does not appear on my other browsers (IE6, Firefox, etc.)
Given the trouble I had with the hostname containing an underscore (see previous post) I thought I'd try the alternative url. Sure enough! The unwanted headers disappear! UH?!?!
Using the machine name and accessing the site with that as the hostname: no unwanted header text and no "script error."
Using the Alternative Access Mapping as the url: unwanted header text is visible and many script errors.
And IE script error messages are so helpful, too.
Line: 1257
Character: 57
Code: 0
Error Message: Expected ')'
But an Add-on called "DebugBar" (available on the IE7 Add-ons website) provides a "IE Interpreted Source Code" view. Nice. Too bad line 1257 had nothing to do with anything and just some innocent table tags. I'm still not sure I'm seeing "Line: 1257" Is it possible to see Line 1257?
I've Googled this but no one else seems to have been bothered with this…Mmmmm…
seanharrison