PowerMac G4 Gigabit Ethernet won't stay turned off

[Chrispy]

I have an upgraded PowerMac G4 gigabit Ethernet that will not stay turned off. When I shutdown the computer turns off and then turns itself right back on again. It started this after I was gone for a weekend and has done it ever since. Has anyone else experienced this problem? I tried resetting the PRAM and checked the system memory as well as reparing disk permissions. Any help or ideas would help. Thanks!

 

[iMeowbot]

You might want to try resetting the PMU. http://docs.info.apple.com/article.html?artnum=95037 Only press the button once, as Apple warn.