I have this problem too. Often times, but not every time, when the system goes to sleep it actually shuts down completely. If I had IE open, my session ends unexpectedly. If I have a word document open, it is gone unless there happened to be an autosave.
The troubleshooter did nothing. In advanced power settings, the close lid and power button both are set to sleep. What exactly am I supposed to do once I reboot in safe mode or clean boot in order to fix this?