update errors eo media php

I just upgraded to 3.5.1. I kept my current config file and uploaded it after the update. I can’t even access the log in any more.

I get this error:

Fatal error: Cannot redeclare class WP_embed in . . .
and then it shows the path to my wp_includes folder to the media.php file on Line 1040.

class WP_Embed {
	var $handlers = array();
	var $post_ID;
	var $usecache = true;
	var $linkifunknown = true;

I put it into Dreamweaver to look at the code and it shows no syntax errors.

Would this have anything to do with a plug-in? I only had 5 photos in the library and 4 were in Slideshare.

Any help appreciated. Slideshare is licensed, but all plugins were updated before the WP 3.5.1 update was done.

Thanks,

Helen