When you run System Monitor on a Windows XP SP1 computer, the default performance objects, Memory and Performance, are missing from the System Monitor GUI (Graphical User Interface).
This behavior can occur if an administrator has used a policy, or a program, to place restrictions on performance object registry settings.
To workaround this behavior:
1. Install the latest Windows XP service pack. See How do you obtain the latest Windows XP service pack?
2. Open a CMD.EXE window.
3. Type the following command and press Enter:
REG ADD HKLM\SYSTEM\CurrentControlSet\Services\PerfOS\Performance /V "Disable Performance Counters" /T REG_DWORD /F /D 0
NOTE: You may have to contact the administrator if you do not have write permission on the above key, or if a policy causes the setting to revert back when you restart the computer.