Hello Hernanhr,
If you are using NISE version 2.0, then running the attached registry file will update your registry with a fix and you shall have access to NISE from accounts other than Admins. Please back up your registry before you run the attached fix. In case you run into any problems, you can restore the older registry file. To back up your registry, go to Start -> Run -> Type "regedit" -> File -> Export.
If you are using a version other than 2.0. Please let me know.
Ayman K