This may not mean these accounts are not in the Administrators group, but it
may be damaged Access Control Lists, some aspects of NTFS and Windows
Registry that you need permission over have lost their Full-Control rights
for Administrators and possibly the SYSTEM user.
Microsoft's SubInAcl.EXE (part of the Windows Resource Kit and its own
topmost link in Google) is often used to correct this particular fault,
typically picked-up by Setup failures, e.g. in the Windows Registry:
http://blogs.msdn.com/astebner/archi...04/739820.aspx