Computer Shuts Off

My computer works fine, but when I put it on standby and come back in an hour (or two or three), I hit the space bar or move the mouse to make it wake up, it turns itself off. I've always done it this way and it just started doing this recently. Any ideas? Thanks in advance - rPm

 

Boot your PC and go in to the Bios, take a look at any options that are associated with the Hibernate or Sleep state, see if they have been set to S5. If so then this is the cause of your PC restarting when you try to reawaken from Hibernate / Standby you want to set it back to either S1 or S3.

 

There's nothing in my bios that relates to the sleep mode or hibernating. Didn't see anything that resembled S5, S1, or S3 either. Nothing unusual has happened (power spike, etc.) that would alter my bios, but thanks for the idea. Any other possibilities come to mind?

 

Sorry about that, my computer is a HP Pavilion a500n, operating system is indows XP, and it's a desktop. Also, I am using a Microsoft wireless keyboard and mouse that are not original but appear to be working fine. This problem started a couple of weeks after I started using this keyboard and mouse but I went back to the originals (wired) for a couple of days but I still have the problem. Thanks for your input - rPm

 

Tried all of the suggested remedies from HP support that you suggested in addition to step 5, and reset some network settings but did not fix problem. Now I have a message when I turn off the computer in its own window: "session controller:lxdf - do you want to end the session now?" And I don't have an iPod connected to computer. I'll keep banging away at it and I do appreciate your help - rPm

 

Try the Power options. Control Panel>Power Options

 

Been there, done that - tried various settings and combinations to no avail but thanks for your interest. - rPm

 

Hate to spin your wheels but I was wasting so much time trying to fix this problem, it just seemed easier to do a system restore and start over. Everything is OK now but thanks so much for all your efforts. - rPm