Our client is running a Dell PowerEdge 2900 with a PERC 6i RAID controller and Windows Server 2003 Small Business. It's running Active Directory, Exchange, DNS, and DHCP. Software installed is Syspro, and Viper Antivirus. No changes to the server have been made within the past couple of weeks other than installing the Antivirus and changing the Administrator password (which has since been changed back). In case it may be relevant, my first step I took was to reserve the UDP ports for IPsec and Viper Antivirus in the registery due to an error in the event log, and because the server would not get online.
The problem started with the server rebooting itself a couple of times and would hang at "Applying Computer Settings" until it would eventually lock up (meaning the mouse and keyboard are non-responsive and a hard reboot is required). Safe mode works all the time, with networking works sometimes, and normal boot works fine if I unplug the network cable. It takes a VERY long time to boot when booting in normal mode. I also found that if I turn off the DNS Server service that the system boots into normal mode fine. If at any point I turn DNS Server back on, after about half an hour, the system will go unresponsive with no HDD activity and a hard reboot is required. At this point there aren't any key events in the Event Log but there are a few misc events regarding a general problem with Active Directory.
What do you recommend as a next step in troubleshooting? This problem is urgent as our client is totally down at this point and we've been troubleshooting for 2 days now. I'm offering 500 points to whoever resolves the issue!