@maxd wrote:Sorry Bill. At this point I can only throw out some ideas. If it's just a case of putting the tab back in a registry edit or creating a 'show ups tab' might solve your problem.Have you run the "sfc /scannow" command ?Is there a snap-in that you could re-apply ?Have you confirmed that that model is XP-compatible, ie MS HCL ?Do you have the most recent APC software installed ?Are all device drivers (including hidden ones) working and enabled ?Do you have sufficient rights ?Have you tried with and without APC Power Chute sw installed ?Did you see the answer to your TechArena post re COM ports ?Have you done up-to-date virus and spyware scans ? (Something knocked out the tab.)I have a few links to post but review the ideas I've thrown out and get back to me. Would you say you're an advanced computer user ?