Enter SETUP (BIOS) and see if it is enabled or disabled in there. To enter SETUP depends on the make of computer but sometimes it is hitting the "delete" key at the post before Windows loads. Sometimes it is the F1 or the F10 keys. Sometimes if you watch the computer screen when you first turn it on, it will tell you what to push to enter setup. This option only last a few seconds so watch closely. BTW, Standby mode on some XP configurations can be shakey.