Standby/Screen saver

Hi The power setting on my computer is set for one hour to go into Standby mode but it does not. The BIOS is set for standby and so is my power options dialog box. I can do a manual standby which does not always work properly, i.e., sometimes it will come right back on; sometimes it will come awake in 15, or 20 minutes, or sometimes it will stay on standby (the longest time was (7) hours) until I move the mouse. I have also noticed that my screen saver does not come on automatically either. I have two auto update programs running on the startup menu but in the past this did not cause a problem. Has anybody had this same problem and if so how did you solve it? Thanks