Reposted from a quote by Aryeh Goretsky: There are a number of reasons Microsoft's Windows Security Center might not recognize NOD32. The most likely one is that Windows Management Instrumentation's (WMI) core repository of information about what software has been installed on the computer is corrupt. Here are the steps to reset WMI's core repository: 1. Open a Command Prompt by clicking on Start->Run, entering "CMD.EXE" as the name of the program to run, and click on the OK button. The Command Prompt window will appear. 2. In the Command Prompt window, type "NET STOP WINMGMT /Y" and press Enter. 3. Type "REN %WINDIR%\SYSTEM32\WBEM\REPOSITORY %WINDIR%\SYSTEM32\WBEM\REP.OLD" and press Enter. 4. Type "EXIT" at the Command Prompt to close the window. 5. Reboot the system. Windows should start up as it normally does, but you may be prompted to reboot the system once more in order to finish making the changes to the system caused by resetting WMI's core repository. Allow the computer to reboot if it prompts again. You may also need to reboot a second (or third) time if the Windows Security Center still does not detect NOD32. The Windows Security Center should now properly detect NOD32 and report it as being current. If it does not, go ahead and try reinstalling Service Pack 2 for Microsoft Windows XP. NOTE: I have not been able to actually reproduce this problem, so if this resolves the issue, please let me know. Thank you.