Hibernation is a process that uses Hyberfil.sys. As does Fastboot. Of the 2, it's almost always Fastboot where the problems lie. When you shut the pc down, windows, through Hyberfil.sys, saves all the drivers etc that's currently loaded in the system ram to the storage, under Fastboot. When you turn on the pc, windows Fastboot grabs all those drivers back. If there's a corrupted, out of date coded, conflicted driver in that batch, it gets returned as is, and you got issues. If, for any reason, the pc gets hung, restarted, rebooted before windows fully loads, it'll restart but as a Cold boot, which does not simply return the Fastboot drivers, but instead loads all the necessary drivers from scratch. Consequently your startup goes from 20 odd seconds, to 50 odd.
The gimmick of it all is that disabling hibernation does nothing for Hyberfil.sys, it still functions, just as disabling Fastboot doesn't affect Hyberfil.sys. And windows will get sneaky at times and re-enable them with power setting changes or updates, as it sees them as optimum settings.
http://www.sevenforums.com/tutorials/819-hibernate-enable-disable.html
The only way to prevent this is delete Hyberfil.sys permanently. Works for any windows platform.
Oh, and Hyberfil.sys apportions 75% of your total ram size from C drive, as unusable, so if you have 16Gb of ram, you loose @12Gb of your C drive. Deleting Hyberfil.sys means windows will no longer need to do that, so you get back what was stolen. This is of real importance to those using smaller SSDs like 120Gb, with 16Gb or more ram. If you have a 120Gb ssd and run 32Gb of ram, that's 24Gb of SSD space stolen and unusable.