Feed error: White spaces are required between publicId and systemId

[MissMalaprop]

I've searched the forums and saw this exact question posted a number
of times with no answer. My feed recently stopped working and when I
try to resync I get this message:

"The URL you entered does not appear to be a valid feed. We
encountered the following problem: Error on line 1: White spaces are
required between publicId and systemId."

Here is my original feed:
http://www.missmalaprop.com/feed/

Any clues on what happened and how I can fix this?

Also, on an unrelated note, does anyone know how to change the email
address that your feed is associated with, ie the address you
originally created the Feedburner feed with? When I created the feed
over 3 years ago I used a Yahoo address, and now even though my main
Feedburner account is associated with a different email address, my
email subscribers still see the Yahoo email as the "from" address in
their email feed. I would love to be able to change this...

Thanks!
Mallory

[MissMalaprop]

I subscribe to my own feed via email, so I think that my post from
Friday, February 19, 2010 is the last post that worked correctly:
http://www.missmalaprop.com/2010/02/friday-links/

I saw something somewhere that mentioned if you copy and past things
into Wordpress from Microsoft Word that it can sometimes cause this
error in the feed... I avoid doing that, so I don't think that's how
it happened, but I checked over the html for the posts I've made since
that date and couldn't find any strange formatting. I also deactivated
a bunch of plugins, hoping that one of them was causing this error,
but I'm still getting the same message.

I've searched and searched and I've seen this same question asked all
over the place with no real answers on how to fix it. I did have over
1,100 subscribers and now no one is getting my feed! Any help would be
greatly appreciated.

Thanks,
Mallory