One of my seniorweb clients reports: (Win XP Home)
The standby/hibernate button (SYSTEM turn off) has become grey. When going to the hibernate tab has also disappeared as well the bottom options in power schemes (the one that set system standby and system hibernate).
It may have happened during the installation of new printer drivers but the user does not want to restore as apparently it took a long time to find and install the correct new drivers.

Can anybody advise how to get the power management back?This usually happens when you install a device driver that is not power management compliant, so I'm afraid you've got your answer right there.Thanks Rob; I had not SEEN this before, but it makes total sense (in retrospect).
I have asked the user to bring his computer to me and will start CHECKING all drivers.Is the printer in question particularly old?  I guess the user may just have to live with it, if that's the case.I do not know: it is a HP laser printer and they, apparently had all kind of problems installing it in the first place.
But it is definitely not new, as a son of the owner has returned home (temporarily) PENDING a divorce etc. and BROUGHT this printer with him.
Anyway, I will get the system next week and check for myself; see what can be done. And, I guess, the printer will be there for a limited period of time anyway.
My mistake was that I did not link the printer driver with power management.
Thanks again for your support.