Have you made any custom changes to the portal? Perhaps you applied a theme and there was no dockbar code in the template or may be some changes through permissions?
Once you login using /c/portal/login with admin credentials, try accessing the control pane using it's url (for 6.1) http://localhost:8080/group/control_panel?doAsGroupId=10180&refererPlid=10183

Checkout this post as well http://www.liferay.com/community/forums/-/message_boards/message/13499171

As Gregory indicated in his post it's something of a glitch.
According to portal.properties, this will disable fast load of javascript meaning it will not load the packed version of javascripts that might cause this problem.