So I'm banging my head on a problem

Our office just moved and we had trobule getting our ADSL lines moved across because optus and telstra are fantastic.

We finally got one line yesterday and the network was working good till about 2pm then it seemed the router would non longer route traffic to worksations or servers but could still see the internet.. Any where I could start tried rebooting tried different routers, tried conecting with the modems that works but I as soon as I turn DHCP off on them they stop routing to the network.

ip range is 10.0.0.1-255 subnet is 255.255.255.0

Also I tried robooting our SBS server which is now not responding to RDP and stuck at a "applying computer settings..." screen. It logs in in safe mode.

Ok so its locking up on a service

Try letting it boot normally and just wait, you will find the service will fail then it will move on. Once in check what services have not started correctly check whats in the event logs

Or start in safe mode disable exchange and sql then reboot normally then start investigating what went wrong

Also what av / security is installed

Also what hardware is it installed on

Is the gateway/dns assigned to clients the SBS server or the router?

What's doing your DHCP and also what is doing your DNS? SBS should be doing your dns and then forwarding to your router so make sure you have forwarding in place on your SBS server
http://www.youtube.com/watch?v=D344cPx9d_I