"All of a sudden my netgear wont assign my isp's ip address"
The router will never assign your WAN IP address (provided by your ISP) to the computers connected to it. It must allocate a LAN IP address to each computer connected to it and "route" the internet traffic to that LAN address. Otherwise, there would be no point in having a router as only one computer - the one with the WAN address - would have internet access.
As far as DNS Server addresses are concerned, routers can behave differently - some allocate only their own IP address, some allocate their own IP address plus one of the ISP's DNS addresses and some pass both ISP DNS addresses through. However, if you're having problems with DNS, you can allocate the server addresses manually without changing the IP address setting which can remain automatic by DHCP.