Unable to mount 80 GB Filesystem

Hi there,
I have a new Mac for two days and today for the first time this error appeared on my desktop after the startup finished to load. Is my first Mac and I am lost with this error. Please experts help me to fix this !
Why I have this error and is a system error or a user error ?
Thanks !

Unable to mount 80 GB Filesystem
Error mounting: mount exited with exit code 1:helper failed with: mount:only root can mount/dev/sda7on/media/80GB
OK
