SQL server agent- agent Xps disabled

I followed the instruction suggested in this post:

sp_configure 'show advanced options',1

go

reconfigure with override

go

sp_configure 'Agent XPs',1

go

reconfigure with override

go

sp_configure 'show advanced options',0

go

reconfigure with override

go

But it didn't work properly and SQLAgent service stops again:

log:

2013-12-11 11:49:32 - ? [100] Microsoft SQLServerAgent version 11.0.2218.0 (X64 unicode retail build) : Process ID 9440
2013-12-11 11:49:32 - ? [495] The SQL Server Agent startup service account is IT\SPAdmin.
2013-12-11 11:49:32 - ? [000] Configuration option 'Agent XPs' changed from 0 to 1. Run the RECONFIGURE statement to install. [SQLSTATE 01000] (Message 15457)
2013-12-11 11:49:32 - ? [101] SQL Server SPQC version 11.00.2218 (0 connection limit)
2013-12-11 11:49:32 - ? [102] SQL Server ODBC driver version 11.00.2218
2013-12-11 11:49:32 - ? [103] NetLib being used by driver is DBNETLIB; Local host server is 
2013-12-11 11:49:32 - ? [310] 4 processor(s) and 8088 MB RAM detected
2013-12-11 11:49:32 - ? [339] Local computer is SPQC running Windows NT 6.1 (7601) Service Pack 1
2013-12-11 11:49:32 - ? [432] There are 12 subsystems in the subsystems cache
2013-12-11 11:49:42 - ! [364] The Messenger service has not been started - NetSend notifications will not be sent
2013-12-11 11:49:42 - ? [129] SQLSERVERAGENT starting under Windows NT service control
2013-12-11 11:49:42 - ! [298] SQLServer Error: 22022, Usage:  EXECUTE xp_sqlagent_notify 'A', NULL, NULL, <alert_id>, <action type> [SQLSTATE 42000] 
2013-12-11 11:49:42 - ! [442] ConnConnectAndSetCryptoForXpstar failed (0).
2013-12-11 11:49:42 - ? [000] Configuration option 'Agent XPs' changed from 1 to 0. Run the RECONFIGURE statement to install. [SQLSTATE 01000] (Message 15457)
2013-12-11 11:49:42 - ? [098] SQLServerAgent terminated (normally)

Please help me to solve this issue.