[gdm-list] Messed Up User on GDM

[asif akhtar <akhtar asif gmail com>]

I was trying to create a user in Xubuntu and seem to have messed up the user group serial numbers .. initially i got an error message saying no such user a couple of times. When I restarted the machine I would get an error loading GDM saying user gdm does not exist leading straight into the console. 

Whats the easiest way to fix this issue? 

Thanks for going through this and helping out!