Server 2008 domain no internet with dhcp

We did a new server 2008 installation (the old server croaked and the system state backup was corrupt) and all the data's safe and accessible.  So we're good EXCEPT today (about a week after the new install) internet access dropped off altogether.  The exception was on one computer that had a static ip address.  So we made the other 6 static ip addresses and now we have internet access. But WHY would internet access drop?  The dns records AND the dhcp records all showed the same ip configs, they were all pointed right, all authenticated on the domain, and no errors showing on the event viewer.  We have a Qwest modem providing internet access, with a stand-alone Linksys router for wifi access, and a cisco switch.  The phones are all Cisco VOIP phones, and the computers connect to the telephones to get network access if that helps.