sir i have alreary installed windows 7 ultimate and when i tried to install ubuntu 12.04 it's installer didn't detect windows even i have only two primary and two logical partition on windows when i goes through try ubuntu and use command " os-prober" it shows output like as "

unshare failed: Operation not permitted ERROR: you must be root ERROR: you must be root ERROR: you must be root ERROR: you must be root ERROR: you must be root ERROR: you must be root mkdir: cannot create directory /var/lib/os-prober/mount': Permission denied mkdir: cannot create directory/var/lib/os-prober/mount': Permission denied mkdir: cannot create directory /var/lib/os-prober/mount': Permission denied mkdir: cannot create directory/var/lib/os-prober/mount': Permission denied mkdir: cannot create directory `/var/lib/os-prober/mount': Permission denied"

so plzzzz help me what should i do ???