Might try this...
Downloading and installing the MMC 3.0 for Windows XP is a breeze. However, you must manually enable the new user interface by adding a key to the registry. Here's how:
1.Download the Microsoft Management Console 3.0 for Windows XP from the Microsoft Download Center.
2.Locate and run the WindowsXP-KB907265-x86-ENU.exe executable file to launch the MMC 3.0 installation wizard.
3.Once the installation is complete, launch the Registry Editor (Regedit.exe).
4.Go to HKEY_LOCAL_MACHINE\ SOFTWARE\Microsoft\MMC.
5.Right-click the MMC subkey and select New | Key.
6.Name the key UseNewUI and press [Enter].
7.Close the Registry Editor.
Now when you launch MMC.exe from the Run dialog box, you'll be able to take advantage of the new Add or Remove Snap-ins interface. You simply scroll through the available snap-ins in the left panel and click the Add button to build your custom console in the right panel.
Notes: This tip applies to both Windows XP Home and Professional, but requires that Service Pack 2 is installed.
What caused this current issue / when did it happen? A lot more info would be helpful.
Alan <><