Server reboot hangup

Hi, everyone, I am fairly new here so hello. I hope I am posting this question in the correct place, so sysadmins please let me know if not. The question I have is this, I have 2 Leopard servers on my premisis, both run on intel Mac Pro type hardware, lets call them server1 and server2. Server1 specs: MacPro 2 x 2.0 ghz Dual-Core Intel Xeon, 3gb ram OS X Server 10.5.7 fully updated, Running Services are: AFP, DHCP, DNS, Firewall, Mail, NAT, NFS, Open Directory, SMB this is a secondary dns, and secondary mail server, the main task is to serve AFP, and share an internet connection with about 15 clients, mac and pc. SMB is set as a standalone server. It is also an open directory replica. Server2 specs: MacPro 2 x 2.8 ghz Quad-Core Intel Xeon, 6gb ram OS X Server 10.5.7 fully updated, Running Services are: AFP, DHCP, DNS, Firewall, Mail, MySQL, NAT, NFS, Open Directory, SMB, Software Update, Web, NTP, Time Machine Server this is a primary dns, and primary mail server, the main task is to share an internet connection with about 32 clients, mac and pc. SMB is set as a PDC. It is also an open directory master. Both servers run for 6 to 10 days before they get rebooted, but when they do, it just does not work, sometimes I can sit for over an hour with a spinning circle before I manually have to shut it down, sometimes after about 10 minutes the mouse arrow will reappear and I can go and open the terminal from the dock and type sudo reboot, this then does the job in a matter of seconds, my question is why? firstly and secondly would it be advisable for me to just always use the terminal or does it do a dirty job of rebooting. If it helps I can try get some logs together. let me know. Thanks to all :oops: