phranque - 6:08 am on Jun 29, 2010 (gmt 0)

one of the major advantages to how DNS works is that you can specify multiple servers and you should do so in such a way that maximizes redundancy and autonomy.
in other words you want to avoid a single point of failure.
ideally the servers you specify would be on different class C networks, geographically diverse, and owned & operated by different organizations.

so i'm not sure exactly what you're describing but it sounds likely that there is too much sharing of resources among your name servers and between your name servers and your web server.