Is it actually starting the hibernation sequence? If itīs not, you probably just donīt have the polarity correct for the motherboard shut-down button line. In addition, with Win7 you usually do have to modify the advanced power management settings for the power button functionality.
If the polarity for the shutdown leads is backwards, itīll usually get the start-up pulse, but it wonīt see the shut-down, and then the PSU will hard-off eventually leading to the conditions you mention. But check your power management first in Win7 to make sure youīve altered it correctly and saved it.
Eh, just me, but I never really got hibernation, other than saving a few seconds I just prefer it to fully shutdown/startup fresh. *shrug*