error after mint upgrade from 14 to 15

i just upgraded linux mint to 15 (oliva), when i tried to log in after the reboot, and error message appeared saying there was an invalid line in the login window script, when i logged in, i didn't have a task bar, no access to the menu, i can access the terminal, but don't know what to do, how do i fix this?


specs: Early 2011 Macbook Pro Intel Core i5 2.3GHz 4GB ram 500GB hdd OS X 10.8.3 and Mint 15 (was 14)