Este es un truco tomado del un foro de Microsoft TechNet, y nos permite que se vuelva a activar el Centro de Seguridad de Windows 7, que por alguna razón desconocida ha dejado de funcionar y no nos permite activarlo de nuevo.

Por lo menos a nosotros nos funcionó en una empresa a la que le llevamos el mantenimiento.

Se trata de crear un archivo de texto y pegarle este contenido:

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\wscsvc]
“DisplayName”=”@%SystemRoot%\\System32\\wscsvc.dll,-200”
“ErrorControl”=dword:00000001
“ImagePath”=hex(2):25,00,53,00,79,00,73,00,74,00,65,00,6d,00,52,00,6f,00,6f,00,\
74,00,25,00,5c,00,53,00,79,00,73,00,74,00,65,00,6d,00,33,00,32,00,5c,00,73,\
00,76,00,63,00,68,00,6f,00,73,00,74,00,2e,00,65,00,78,00,65,00,20,00,2d,00,\
6b,00,20,00,4c,00,6f,00,63,00,61,00,6c,00,53,00,65,00,72,00,76,00,69,00,63,\
00,65,00,4e,00,65,00,74,00,77,00,6f,00,72,00,6b,00,52,00,65,00,73,00,74,00,\
72,00,69,00,63,00,74,00,65,00,64,00,00,00
“Start”=dword:00000002
“Type”=dword:00000020
“Description”=”@%SystemRoot%\\System32\\wscsvc.dll,-201”
“DependOnService”=hex(7):52,00,70,00,63,00,53,00,73,00,00,00,57,00,69,00,6e,00,\
4d,00,67,00,6d,00,74,00,00,00,00,00
“ObjectName”=”NT AUTHORITY\\LocalService”
“ServiceSidType”=dword:00000001
“RequiredPrivileges”=hex(7):53,00,65,00,43,00,68,00,61,00,6e,00,67,00,65,00,4e,\
00,6f,00,74,00,69,00,66,00,79,00,50,00,72,00,69,00,76,00,69,00,6c,00,65,00,\
67,00,65,00,00,00,53,00,65,00,49,00,6d,00,70,00,65,00,72,00,73,00,6f,00,6e,\
00,61,00,74,00,65,00,50,00,72,00,69,00,76,00,69,00,6c,00,65,00,67,00,65,00,\
00,00,00,00
“DelayedAutoStart”=dword:00000001
“FailureActions”=hex:80,51,01,00,00,00,00,00,00,00,00,00,03,00,00,00,14,00,00,\
00,01,00,00,00,c0,d4,01,00,01,00,00,00,e0,93,04,00,00,00,00,00,00,00,00,00

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\wscsvc\Parameters]
“ServiceDllUnloadOnStop”=dword:00000001
“ServiceDll”=hex(2):25,00,53,00,79,00,73,00,74,00,65,00,6d,00,52,00,6f,00,6f,\
00,74,00,25,00,5c,00,53,00,79,00,73,00,74,00,65,00,6d,00,33,00,32,00,5c,00,\
77,00,73,00,63,00,73,00,76,00,63,00,2e,00,64,00,6c,00,6c,00,00,00

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\wscsvc\Security]
“Security”=hex:01,00,14,80,c8,00,00,00,d4,00,00,00,14,00,00,00,30,00,00,00,02,\
00,1c,00,01,00,00,00,02,80,14,00,ff,01,0f,00,01,01,00,00,00,00,00,01,00,00,\
00,00,02,00,98,00,06,00,00,00,00,00,14,00,fd,01,02,00,01,01,00,00,00,00,00,\
05,12,00,00,00,00,00,18,00,ff,01,0f,00,01,02,00,00,00,00,00,05,20,00,00,00,\
20,02,00,00,00,00,14,00,9d,01,02,00,01,01,00,00,00,00,00,05,04,00,00,00,00,\
00,14,00,8d,01,02,00,01,01,00,00,00,00,00,05,06,00,00,00,00,00,14,00,00,01,\
00,00,01,01,00,00,00,00,00,05,0b,00,00,00,00,00,28,00,15,00,00,00,01,06,00,\
00,00,00,00,05,50,00,00,00,49,59,9d,77,91,56,e5,55,dc,f4,e2,0e,a7,8b,eb,ca,\
7b,42,13,56,01,01,00,00,00,00,00,05,12,00,00,00,01,01,00,00,00,00,00,05,12,\
00,00,00

Guardarlo como FixCentro.reg por ejemplo, y ejecutarlo como administrador.
Reinicia y trata de activarlo de nuevo. Ahora debe de activarse sin problemas el Centro de Seguridad de Windows 7.