I just want to say I had this exact same problem and stumbled on this thread while finding solutions. It's like moments after my computer goes to sleep it wakes up again:
[From System Event viewer]
The system has resumed from sleep.
Sleep Time: 2012-08-05T12:11:20.127805700Z
Wake Time: 2012-08-05T12:11:44.470007000Z
Wake Source: Device -ACPI Power Button
[From cmd: powercfg -lastwake]
Wake History Count - 1
Wake History [0]
Wake Source Count - 1
Wake Source [0]
Type: Device
Instance Path: ACPI\PNP0C0C\3&2b8e0b4b&0
Friendly Name:
Description: ACPI Power Button
Manufacturer: (Standard system devices)
And what I did was disable the "Wake on Lan" option from my BIOS settings, and everything worked out again perfectly. I followed the solutions from this page:
HTML:
http://superuser.com/questions/397686/vista-laptop-keeps-waking-up-a-minute-after-i-put-it-to-sleep
This is what I did and works for me.