Help Please

After updating today, My admin screen went blank and keep on getting a 500 error for admin.

below is what firefox is displaying for error
[code]
Timestamp: 3/6/2013 10:33:28 AM
Error: The character encoding of the HTML document was not declared. The document will render with garbled text in some browser configurations if the document contains characters from outside the US-ASCII range. The character encoding of the page must be declared in the document or in the transfer protocol.
Source File: http://joseph.heavenboundministry.com/jjblog/wp-admin/
Line: 0
[/code]

Internet explorer displays
[code]
Most likely causes:
•The website is under maintenance.
•The website has a programming error.
[/code]

Help Please. . .

http://wordpress.org/extend/plugins/extensible-html-editor-buttons/