I'm not sure if this is your case but here it goes.
When you do not use your computer for a specific period of time it will go to sleep.
Prior to going to sleep it must update the hibernation file in the C: drive root directory.
You will not see this file as it is hidden. So whatever may be left open an unsaved is stored here until you wake it up. Such as a word document or excel spreadsheet that was not saved. When you wake up some memory has a little problem and freezes the system.
OK, Now you return and want to wake your computer up. Not sure how you do it but I just hit me start button and everything starts back up.
Before the computer starts backup it tried to read the hibernation file and get you back where you were.
I have heard in the past year many times this doesn't work right. Can't tell you why but at least this is a start.
I personally have shut down the making of my hibernation file and do not use it on my desktop or laptop. It makes the bootup longer and the file can be very large in size.
If you want to check out how to shut down the hybernation file/more look under control panel and Power Options. You may find more here on step by stepp. Maybe someone will jump in and help more.
This is just my thoughts what could be your problem.
Good luck and keep us posted on your solution.
Here is the tutorial on how to Disable/Enable Hibernation Mode.
Hibernate - Enable or Disable