April 2013 CU - Security Validation issues

Our farm was upgraded to the April 2013 CU from August 2012 CU.

This caused an issue with publishing page layouts which had Managed Metadata fields embedded in them.

Disabling Security Validation fixed this, same as suggested here:

http://www.sharepointblog.co.uk/2013/04/sharepoint-2010-taxonomy-errors/

Now after disabling security validation, new list/library/site screens no longer work.

Same as the issue listed here: http://spcodes.blogspot.co.nz/2012/12/an-unhandled-exception-occurred-in.html

So I can't figure out a way to have both functionalities working a the same time.

Any ideas?