Hi NavneetDo check out whether the username/password which you are using to login via the console is configured with privilege level 15...You can configure a username/password with level 1 or level 2 after which you can get in using enable secret/pas...

Hi Kimbelow mentions the importance of the command network-clock-participate and also the effects once its keyed in..http://www.cisco.com/univercd/cc/td/doc/product/software/ios123/123tcr/123tvr/vrht_n1.htm#wp1016893regds