[Genome Soldier]

I know this isnt tech support but... I need help.
My comp is only like 2 months old. Its a DELL and ive had problems with logging off. When my mom logs off the comp freezes. I am the administrator and my mom and stepdad are limited if that helps.
But I nor my stepdad have problems logging off. I also tried deleting her S\N completely and making a new one but it still freezes. I am about to reformat it but dont really want to. I would rather just fix the prob. Can ne1 plz help me.