I am a computer technician in a high school where none of us are experts but everyone expects us to be!! I currently have a problem I cannot solve. We have a domain server running windows server 2003 with active directory (SP1 installed) plus two other applications servers running student programmes (also server 2003). The network consists of about 200 workstations mostly running windows XP with SP2. For some time we have had a problem with a workstation unexpectedly going offline but this has not been a great problem (it was worst with laptop using a wireless LAN but this improved with better NICs installed). In the last week, howwever, nearly every time someone logs on, student, staff, administrators it makes no difference, the workstation will go offline after a few moments. A window pops up saying " No longer connected to chsserv - working offline. (The domain server is called chsserv). Users can log on okay and use the internet (via a proxy server which is also the DHCP server) but cannot access any share in particular their own home drive. The problem exists over the whole network so I have ruled out faulty switches, NICs etc. You can ping offline machines to one another using IP address or computer names. The only chage made to the network is a new file/applications server and appart from a few recent updates nothing else has changed. As far as I know we have sufficient licences for all workstations but anyway the problem has only just arisen. Netmon, Dcdiag etc offer no obvious solutions! We have Sophos virus software installed on all machines with auto/remote updating. I have spent all today on this problem with no progress. Any help much appreciated.