Resolved: See the comments for resolution.
This is weird. Definitely something to do with my system and the ACPI driver. When I shutdown Windows 7, it goes down and I can hear pretty much everything turning off. But some fan keeps running. When I clicked the power button, nothing happens and then when I press the reset button, the system starts. In my BIOS I have enabled ACPI 2.0 and have set some settings for the fan. Windows is not able to detect those settings I guess.
Here is what I sent using feedback tool.
When I press shutdown, the system doesn’t go down fully. Hard drive, monitor etc are off but I can hear one fan running loud. If I press the power button, nothing seems to be happening (wait for few hours before pressing the power button. In my case the system was in that state over night.) but when I press the reset button, system starts or restarts.
My PC uses ASUS motherboard P5B-E and BIOS version 1802. I have enabled ACPI 2.0 and have set CPU and motherboard fans to silent mode. I don’t think I have a fan controller connection to the power supply.
Update: Disabling Hybrid Sleep and all other power management stuff didn’t help. What is system cooling policy?
Resolution for M-Audio audiophile Delta 249 conflict.
Similar to the issue discussed in this article but an add-on card.

same problem u have solved???