Hi everyone!

I have a strange problem. I have two 24 port gigabit switches and a d-link DIR-2640B adsl modem with 30 or more connected computers. The last two days im having problems connecting to internet. As long as i connect my adsl modem to one of the switches (the switches are bridget together) i loose internet connectivity. Cannot ping anything online. When i access the web interface of the modem, it is everything fine. ADSL is synchronized, connected, and has everything fine. If i diagnose the connection from the modem, it fails. As long as i disconnect the modem from the switch and connect ti directly to one computer, the internet works fine. Can someone give me some help about this problem?