500 error with Feedburner plugin

Seems to be a conflict between the feedburner htaccess code and my permalink htaccess code. Here’s my permalink structure:
/posts/%year%/%monthnum%/úy%/%postname%/

Any ideas?

Error log says “bad flag delimiters.” Any ideas?

Got my front page and back end to work again by deleting most all of my htaccess file. But now my permalinks don’t work. And the feedburner redirect won’t work either (since that’s all in the htaccess file, or was, before I deleted it.)

If I try to reactivate permalinks via WordPress, I get a 500 error again. Don’t know why this would cause a problem, since I’ve always had permalinks—and with this structure.

There is no such %y% permalink tag.

Was that supposed to be %day% ?
Here’s what I see:
/posts/%year%/%monthnum%/???y%/%postname%/
Here’s what it should be:
/posts/%year%/%monthnum%/%day%/%postname%/

Apologies to all for my little panicked self-conversation here. 404 errors I don’t too upset about, but a 500 across the whole site makes me want to cry. ??

Turns out the problem was a space in the Feedburner url. I’m pretty sure I pasted it in, so I’m not sure how that happened. So we’ll just call it my bad and I’ll go hide now.