When you install SP4 on a client computer, domain logon scripts no longer run. If you remove SP4, the logon scripts run. The Userenv.log file may contain:
USERENV(1418.15b8) time CheckXForestLogon: checking x-forest logon, user handle = 124
USERENV(1418.15b8) time CheckXForestLogon: policy set to disable XForest check
This behavior will occur if the logon script is configured in a user policy from a trusted Windows 2000 forest AND the new Allow Cross-Forest User Policy and Roaming User Profiles policy has NOT been Enabled.
NOTE: SP4 includes this new functionality to increase security between Windows 2000 forests.
To resolve this problem:
1. Log onto the client with local Administrator rights.
2. Start / Run / gpedit.msc / OK.
3. Navigate through Computer Configuration / Administrative Templates / System / Group Policy.
4. Double-click Allow Cross-Forest User Policy and Roaming User Profiles.
5. Select Enabled.
6. Press Apply and OK.
7. Exit the Group Policy tool.
8. Open and CMD.exe prompt.
9. Type secedit /refreshpolicy machine_policy and press Enter.