It must be some sort of glitch kguske and nothing related to nukePIE.
I can see the error message in the bottom browser status bar in FF under "HTML TIDY result"
BUT if I validate the page using TIDY from the tools menu, it doesn't show the error message - I wish it did as it would help me track down where it *thinks* there was an error.
All a little frustrating
I know I have other errors due to third party code I'm pulling in elsewhere on the site.
If you have a few seconds to spare, if you could pop over to my site
www.code-authors.com and confirm/deny you are getting the invalid HTML message in the bottom status bar with FF when viewing the main index page that would be great!
Looks like it is just one of those *gremlins* - if TIDY reports an error in the status bar but doesn't show it when validating the page then it's obviously something screwy with the plug-in.