Slow boot at "Applying Computer Settings"

We just now upgraded to Windows 2003 Active Directory and have noticed that our Windows XP SP2 clients are booting vert slowly and stuck for 2-3 minites on the "Applying Computer Settings" screen. Most of the articles that I have read about this issue tells me issues surrounding DNS, but I dont know that our DNS is setup properly or not. We are using the split brain dns solution. The internal Dns servers run Windows 2003 server and are also domain controllers. They are configured to allow DDNS. We have got outside DNS servers that are servicing outside DNS queries. The XP clients point to the Internal DNS servers only and all of our XP clients are properly dynamically registering with DNS in the forward lookup zone. Can anyone tell me how to troubleshoot and find out what is going on inside the "Applying Computer Settings" which is taking so much long time? Thanks.

Could you please type the below at a command prompt from a workstation to check DNS is fine:

nltest /dsgetdc:domain-name.com
nslookup -type=srv _ldap._tcp.dc._msdcs.domain-name.com

If you want to know what is happening when logging on then for more information, search for and enable verbose or userenv logging.

What measure did you take to change the XP clients to point only to internal DNS? Are you using DHCP, or did you change the DNS settings from within the client TCP/IP properties pages? After you have used regedt32 and did a search for the external DNS, what specific keys did you see the external DNS in? Since configuration information is retained in keys like "ControlSet001", "ControlSet002" for backup/LastKnownGoodProfile, the dns setting that you want are in "CurrentControlSet".

Thanks guys for all the info (and humour :-) I have also been struggling with this issue for about 6 months and every time I think I have found a fix it just comes back to haunt me again a week or so later. Here is a bit of my user environment log:

First there is some stuff that doesnt take forever and then there is:

USERENV(7e4.7e8) 13:10:04:909 LibMain: Process Name: C:\WINDOWS\system32\wbem\wmiprvse.exe
USERENV(f24.f28) 13:15:39:920 LibMain: Process Name: C:\WINDOWS\system32\wbem\wmiprvse.exe
USERENV(228.3d0) 13:18:54:259 EnterCriticalPolicySectionEx: Machine critical section has been claimed. Handle = 0x774
USERENV(228.3d0) 13:18:54:259 EnterCriticalPolicySectionEx: Leaving successfully.

then more stuff and then:

USERENV(228.3d0) 13:19:02:575 MachinePolicyCallback: Extension requested status UI when status UI is not available.
USERENV(228.3d0) 13:21:07:302 MachinePolicyCallback: Setting status UI to Applying computer settings...
USERENV(228.3d0) 13:21:07:302 MachinePolicyCallback: Extension requested status UI when status UI is not available.

So it looks to me like the problem is something to do with loading WMI, someone else suggested rebuilding the WBEM repository, but that didnt help. And the weird thing is, I dont have multiple sites so my machines never have to pass my firewall to get to my DCs. Argh! I am thinking of setting my userenv logs to debugger mode in case I can get more info about what calls and things the wmiprvse.exe file is trying to make when it is taking three minutes..