sleep mode

I have a few computers going into standby mode and I cannot figure out why. The BIOS settings have been changed and also the power settings with in the Screensaver applet have all be set not to:
hibernate
sleep
or standby.

This all started when we installed a certain imaging program called RVI. The claim no responsibility of course.

Is there possibly a registry hack that I do not know about in Win XP that stops the computer from going into standby mode? My end users are getting tired of having to sign back in when they leave their computer for an hour or so.

Thanks