I have a dual boot computer running Vista Ultimate and Windows 7 RC.
I built a new computer for my wife and loaded it with just Windows 7 RC pending delivery of the full retail version in October.
Both computers have a similar problem. Sometimes - but not always - after shutting down the computer using the Start>Shut Down button it appears to shut down but has actually gone into a deep sleep and will not restart no matter what keyboard buttons you press. It will also not reboot when you hit the computer start button.
The only way you can switch the computer off is to hold the computer start button down for about 10 seconds - then press it again for a normal reboot.
Both machines are the same - her's more often than mine....(But mine is OK when I use Vista)
this is an easy one , go to control panal/Power options whatever plan has been selected click on change plan settings,then click on change advanced power settings, when the power options window opens select power button and lid ,power button action (in blue) click on this and use the drop down to select shut down , finally click on apply and your done . its the same system as Vista uses.