I had this problem about a year or so ago. With the kind help from a forum contributor, I managed to solve the problem. Unfortunately this contributor is untracesble.
All I remember was this:
Press start > Press control panel> From here on I cannot for the life of me remember what steps I needed to do Please help.
In your control panel are power options, in there, on the left panel, you will see an option to "choose what the power button does", options there will be, put into hibernation, put to sleep, do nothing, etc., select the option you want there.
Hope it helps