Purpletin

I never turn off my pc but have it on standby mode when not using it. It used to go on standby and when I start to be on it again, it would directly go to the desktop, as to where I last left it at. But now, my system restarts after it left standby mode, is this normal for XP? I have tried over and over and looked through my power config properties, etc. but nothing I dont see any solution. I looked through to see if anything under the properties have changed, but everything has remained the same. I seriously appreciate the help. Thanks in advance! Purple