I have a Dell Studio 540 with an ATI Radeon HD 3650 This problem started about 3 weeks ago:
When it enters sleep mode after 30 minutes, and I come back within a couple of hours, it wakes up just fine.
However, when I leave the PC overnight, it does not wake in the morning. A blue box appears saying that it is going into Powersave mode. The only way I can get it going is to turn it off (with the power switch) then turn it on again. Oddly enough, occasionally when I do that it opens with "resuming Windows".
What is going on here? I know that turning the computer off using the power switch is a bad idea but how else can I get the machine to wake up and face the day?