How to Enable USERENV Logging

Userenv logging is useful in troubleshooting and debugging problems with roaming profiles and system policies.

221833 How to enable user environment debug logging in retail builds of Windows
http://support.microsoft.com/?id=221833

Value Path: HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
Value Name: UserEnvDebugLevel
Value Type: REG_DWORD
Value Data: 10002 (hex)
Output: %Systemroot%\Debug\UserMode\Userenv.log