A quick guess - have you removed Builtin\Administrators from the allowed logins? If so, put it back, make it sysadmin and try the patch again.
No promises. That security patch breaks in a thousand ways and has twice as many fixes.
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability