my /feed won't update

hello everyone

my feed won’t update in google reader and and my feedburner email subscribers don’t get the new emails, , although it opens just fine in browsers with latest posts.

and the feed validator gives my this error: Incorrect length of data produced (Server response declares Content-Encoding: gzip; misconfigured server?)

but my feedburner feed is valid.

I installed many plugins in the last couple of days, and uninstall a lot of it. what could possibly be causing this?

please, any idea would help.