Hi guys,
I went to troubleshoot this network,i realised that the users can't access internet without a proxy server ruuning on the network.I had to install and configure one.If i stop it and configure the client browsers to access the internet directly,they can't.The firewall accepts direct access to the internet,so it cannot be the firewall because even when i disable the firewall,things still don't work.I don't know who configured the network before,but i don't understand how it was done.Has someone ever seen such a scenario before?If yes,how is it done.

If the desktop computers are assigned IP addresses from private ranges such as 192.168 or 10.0.0.0 then they won't be able to connect to the public Internet directly without NAT enabled.

There is a linux router which does the translation.THe clients are suppose to access the net through it without neccessarily going through a proxy.Am i correct?
The prob is,when i tell the client browser not to use squid or when i stop squid,there's no web access.Again note,squid is not in transparent mode!

right, well as above, you'd need natting / ip masquerading if you don't want a proxy.

Yes, Go for either masquerading or natting whichever suits you.