cant change to another domain

hi to all

i created a domain using server2003 and made one of my computer its client after few days i deleted the domain and created another one. now the problem i am facing is that i cant change client computer. when i right click on my computer of client computer and go to properties>> computer name both tabs(network ID and Change) are not activate. when i go to device manage i can see several drivers for my nic card and only is working properly. when i tried to uninstall the ones with yellow sign i couldn't do so...... pls tell me how to uninstall drivers and whats my problem in network and how do i get rid of that...