It would seem that if Fred's AD permissions have changed, especially without his knowledge, then he'd have a different experience than the other admins.
If your DNS solution isn't one that does "active" tests to deal with devices that don't comply with Dynamic DNS requirements, it might be possible Fred's trying to get to a device with a stale DNS entry, Forward or Reverse.
If someone's adjusted Fred's NPM account permissions, that might have interesting results, too.
Perhaps most important, if Fred's using a different configuration than the other three administrators (i.e.: if Fred's got a typo in some DNS entry referencing an APE's name), then you aren't comparing apples to apples anymore.
Isolate what's different in Fred's environment since he started experiencing network node addition behavior that is no longer what Fred's peers experience, and you'll be on your way to solving the problem.
Change Management is a great place to research--see if someone recorded a change that could explain this.
NCM might be a useful tool--see if there are interesting configuration changes for the time period immediately before and after Fred started having problems.
Solarwinds products also have logs and histories to review and search; perhaps something changed in Fred's permissions in Solarwinds.
And before you start any of these avenues of research, open a Ticket online with Solarwinds Support. By the time you've exhausted everything here, they'll get back to you and start helping you out.
I am facing same problem of my APE which are running in HA environment. Can any one help me on this issue.bit urgent