Windows Server 2008 Setup help

Hi,

Bought a new server for my work place as the old server was just for files.
I created a domain for all the computers on the network.

All the computers get their internal IP's form the DHCP server and setup so they are pointed to the DNS server also.

Deleted the old shares from the computers and specified a specific root on the hard drive for the files.

Shared the network drive and everyone can see it when we direct all the computers to the server.

But for some reason the shares seem to disappear when i come in the next morning and the old ones come back.

A shared network folder for the old server appears even though the old one is long gone.

also when they want to access the new servers root they need to login (to be expected) with the admin user and password but it never seems to remember.

How do i go about creating user names and passwords for them all specificly instead of logging in to the local computer?

Any ideas?

Thanks alot