I have spent some time studying the reports. The cause of your problem is not presently clear.
The DRIVER_POWER_STATE_FAILURE bug check has a value of 0x0000009F. This bug check indicates that the driver is in an inconsistent or invalid power state.
Source: http://msdn.microsoft.com/en-us/library/ff559329(v=vs.85).aspx
The system log records two occasions, on the 15th and 19th February, when system failure has occurred. On both occasions, as you have noticed, system failure has occurred whilst sleep is in progress. The failure has been in an orderly manner and not an instant shutdown, which would be the result of a total loss of power. This suggests that it is a single driver. I have looked at your motherboard drivers and they appear to be up to date and you have the latest BIOS.
There follows a note by SpiritX which indicates an avenue of enquiry.
That error ( referring to 0x9F ) means a driver is not handling the power state properly. Check in Control Panel - Device Manager to be sure major drivers are not shut off during sleep - double click Display Adapter - NIC and WIFI - Sound and others - Power Management tab - uncheck Allow computer to turn off power. Maybe only one has an issue.
Source: Post by SpiritX in these forums.
I would be interested to know whether the settings for these drivers has been set to Allow computer to off power? Your computer is a laptop so this is the setting I would expect to see as the computer is reliant on a battery.
This leads to a further question. On the two occasions when the error occurred was the laptop connected to the mains electricity supply? Does the battery charge normally? How well does the battery hold it's charge?
You have a strange error occurring soon after the computer is booted " Realtek PCIe GBE Family Controller is disconnected from network". Research revealed that others have noticed the error but I did not see any solutions. It is one of the devices where I have asked you to check the Power Management settings.
You do also seem to have some events recorded after sleep has been initiated, which seems strange. There is no indication that the computer wakes. This is an example " Name resolution for the name talk.google.com timed out after none of the configured DNS servers responded." These refer to the Network. Perhaps the Network is not shutting down when the computer enters sleep.
You have a number of these errors " The driver detected a controller error on \Device\Harddisk1\DR1". Perhaps we should look at this later as there is more than enogh to look at above.