I've seen this happen before as part of the symptoms of a nasty virus.
I have ferreted out everything I can, is there a legitimate way of enabling/disabling access to the task monitor? The particular userid this is happening to is an administrator! How can I turn on her rights?
Yep - it can be disabled by Group Policy ... http://www.windowsnetworking.com/kbase/Win...sXPHomePro.html
Is this a work-owned machine (i.e. it's someone else's and they administer/manage it)? If not, you should be able to reset it via the registry. If it is, then even if you can reset it via the registry, it will probably get changed back.
You could follow this thread here to help get rid of the spyware