Network performing abnormal

Hi

I have one of my sub office network, after we prepare the domain and replaced their hub with a switch gives abnormal operations.

The network goes like this. 1 server, 1 DSL Model shared by all the users through gateway IP config.

what happens is, all of a sudden for the user either the internet or the networked application will only work. For the other one to work, he/she need to disable and enable the Local area connection or restart the PC then the only other thing will work.

Any help is appreciated.

Regards
Ragav