NTFS permissions Users

The local group "users" have the permission "read & execute" on my c drive.
The "domain users" are member of the local group "users ".

So why is it that you cant acces my c drive over the network if you are a member of the domain users with the following command "\\computername\c$" ???

 

Probably because you haven't set up a share permission for them. You need to go to the share tab on the folder, and click on the permissions button. Then set the share permissions.

I would point out that sharing a whole drive is bad practice, and would advise that instead you only share the folders containing the data you wish to share. By setting share access at the root of C:, you are not only making your documents avaible, but also your system files. Even if your users don't mess with these files, trojans running on their systems might.