The Lsass.exe (Local Security Authentication Server) process on your Windows Server 2003 domain controller may hang if you have many external trusts and many simultaneous logon requests that do not specify the domain name.
This behavior will occur because the Lsass.exe process runs out of resources if the 'number of simultaneous logons' multiplied by the 'number of trusts' is grater than 1,000.
To resolve this problem:
1. Install the latest service pack for Windows Server 2003.
2. Open a CMD.EXE window.
3. Type the following command and press Enter:
REG ADD HKLM\SYSTEM\CurrentControlSet\Services\Netlogon\Parameters /V NeverPing /T REG_DWORD /F /D 1