XP home edition, IBM computer. Ignores specified times in Power Options to go into standby. I can select standby from the shutdown screen. Has been occuring for several weeks. No new software or hardware added. Have MicroSoft Security Essentials installed and run frequently, soapparently not a malware issue. Sometimes the system will not stay in standby when put there from the shutdown screen ... rebooting seems to solve this; don't know whether this is related to the above issue.1 person got this answerI do too