Problems with packets locking up network

I have set up a Windows Server 2003 Network. We have decided to go wireless and since then we have had problems. Every morning we have to reboot the routers to get the network going. Once you do that it works for a while but then the networks get inundated with packets from an unknown source which locks up the network. You can’t access the LAN or the Internet. I have several Linksys wireless gateways in place in the building. Is there anything that I can do to find out what is causing the problem?