13fontad,
Welcome back to CH. You have been here before, so you know we need a lot of info before we can help you.
A LAN with over eight computers on at once ought to have a domain controller. Do you understand what this means? Is there a computer that is the domain controller?
You have windows 7 on your computer. Are most or all students use laptops with either Vista or Windowsn7? Do you ever have connectivity issues on yours?
How large is the campus? Is this a wireless or WI-Fri system that covers a large are with two nor more Access Points?
Some security concerns.
The forum will want to know if you have authority to make any changes into the network system and you you have permission to troubleshoot individual computers? Don't you have a teacher nor unteach assistant that has administrative oversight of the network? Can't he/she come to the forum and post a descriptions of the problem?