Installed patch 5344 to version 8.1.1 and frontend looks fine. In Admin I get:
Fatal error: Class 'Mage_Adminhtml_Block_Dashboard_Graph' not found in /home/********/public_html/app/code/core/Mage/Adminhtml/Block/Dashboard/Tab/Orders.php on line 35
Revert didn't help any. Still same error.
RESOLVED: Copied file app/code/core/Mage/Adminhtml/Block/Dashboard/Graph.php back to server. Somehow it had a file size of 0.
Thank you for posting the fix, occasionally, the patch process throws a curveball.