Active Directory users / groups not working too

I am using a windows server 2003 R2 configured as a DNS Server / DHCP /Active Directory / VPOP3(mail server).Everything was running smoothly the previous night , but the following morning I noticed the server was displaying the “Press ctrl +alt +Del To Login” . This made me think that we had a strong fluctuation or something of that sort but when I logged in I met the following symptoms; Internet is functioning properly but no icons in the tub showing network connections, the lower right corner to the start-menu had no icons apart from the date/time and It was impossible to paste and copy anywhere, to and from external devices. I went ahead and checked services.msc, the view to the right side was grayed out, though standard view was alright but some of the services are missing and I can’t seem to “STOP" /"START” etc. I am also getting an error message reading “Active Directory users / groups not working too. Domains not working and more services not working”. Can anyone please help me out with a solution?
