Since I have my new computer & Vista x86 I had problems with putting it into sleep or hibernate state – as soon it went to sleep/hibernate state it would wake up immediately and return to happy working mode (like my children – putting them to sleep is always an adventure). The motherboard is Intel based Gigabyte GA-965P-DS4 and it really shouldn’t have problems. Thanks to the comment of PetarR I soon isolated the problem to Wake-On-Lan feature. For the test I disconnected computer from network (by pulling out the network cable) and it didn’t wake up anymore until I didn’t make him to. Good, but not good enough since I didn’t know how to disable it (WOL was disabled in BIOS already) and I really didn’t have time to play with it as the issue wasn’t critical and I had a lot of other, more important, work to do. Fortunately Alex Feinman (.net CF MVP) suggested device manager’s advanced features and that was it. I right clicked on my network adapter leaf
And computer finally gets some sleep…
Interestingly, this device wasn’t allowed to wake the computer even before.
Note that I am not yet on official drivers since Gigabyte didn’t relase them yet.