We run policies as well, what I did was log in as the administrator give them temp admin rights log out then have them log in while I was at their system. Taking over their system I would go in and setup the DNS information, log out and then go in and take their admin rights away. Long process but after applying SP2 I haven't had to do that. If I run into anything else I will let you know. A peer of mine had the same issue, I will talk with him to see if he still has to go in and set the DNS information up. Sorry couldn't be more help. Couldn't hurt to reapply SP2 unless you applied it to resolve this issue. Let me know if you find a fix, could be useful as a FAQ here...
david e
*end users are just like computers, some you can work with...others just need a simple reBOOTing to fix their problems.*