Website Hosting ... Pointing To Server

I dont know where else to post this, but I am having a weird problem that I do not understand.

I have this domain, that I am pointing to a VPS hosting service.

I currently have 2 domains pointing here.

my main domain, works fine. I go to the domain, no issues (www.whiteazn.com)

but the 2nd domain, is where i am having problems (firstbaptisthenderson.org)

It is pointed to the same server.

but the problem is, it seems like the server change, never "propogated" throughout the internet. So, while MOST of the time, it hits the server as I expect, there are times where it goes to the Generic Network Solutions Page Not Found Error (you know, when you just buy a domain, go to that domain and see some generic page there?).

and refreshing, clearing cache, etc, still shows for like 1 minute, then after a bit of refreshing, will see the normal page that should be there.

this happens ever so often. I dont go to it everyday, but i think it does it periodically.

I dont know what the issue is? Both my domains are pointed to:
DNS1547.DIZINC.COM
DNS1548.DIZINC.COM

The change to the DNS servers was made like 6 months ago, and this issue has always shown up.