Thanks for all your replies guys!

Ive temporiarily fixed the problem today, I found out that for some reason all the connected machines kept thinking that the Router was the main domain even though they were still connected up via the switch and then the switch to the server :S:S So then i maunally configured the IP settings on my machine to only change the DNS & WINS IP Address to the actual servers IP Address and then all of a sudden after re-connection it started to Synchronise and it actually worked, so then i tried a couple of the Server programs, they all worked too & then tried the email to see if it conencted to MS Exchange and that worked too.

I applied this to all the other client machines for now just until next week and were all sucessfully using the network properly now. This is the thing i dont get, how come before when all the machines were set to automatically get an IP Address from DHCP through the BT Router and it worked before?, but when i first set it back all up at the start of the week it did not work then?? The IT Manager said that everything should world with an automatic IP Address used from the router but i dont see how this would work? it did not work until i changed on the DNS & WINS details so it picks it all up from the server. Btw the router we have is a BT 2wire Business router.

Thanks again all - Liam

Simple answer. BT routers are as usefull as tits on fish and cant be relied upon for simple things like DNS lookups.  They get confused and clients end up not able resolve UNCs.

Long Answer

I take it then your IT manager hasnt followed Microsoft recomended best practices for SBS 2003 by using dual network card setup and using the SBS as the DHCP and DNS Server, which it should be.  Otherwise that wouldnt be possible.  The Nature of DHCP is that logical addresses change, if the DNS records do not update then machines cannot be found.  Its even possible your SBS doesnt have a static IP which would explain alot.

SBS can be configured in a network in many ways, most of those ways are wrong because they cause real long term problems.

I recently picked up a client whose SBS 2003 server (set up by a gold certified partner???) had one NIC, and the BT Buisness hub was being used as both the DHCP server and DNS for the nework.  Christ the desktops didnt take 5 minutes to logon before I sorted that mess out.  The server wasnt even on a fixed IP?!!!