I started a thread going a few weeks back here:
Basically, I've got Derek Morrison RSSfeed+ block installed. It works fine, but somehow I'm getting the html from block_rssfeed.php printed before the tag of admin/index.php.
This has two effects:
1) the whole page shifts down a couple of lines;
2) when you try to use IE to display the page, the scroll bars disappear, so you can't get to the bottom of the page.
I've tracked down the culprit code to the function upgrade_blocks_plugins in lib/blocklib.php (when you comment out the line that calls it in admin/index.php the page displays fine), but there the trail ends... I just don't know (yet) how to read the code to find out what's happening.
I did think perhaps it was some stray single quotes in my rssfeed titles, but even removing the all the feeds themselves doesn't change anything.
If anyone could point me in the right direction, I'd be very grateful.