Error BCCode: 9F 0x0000009F is likely a driver issue. Antivirus/antispware/security programs can also cause these issues. Have you added devices lately or updated drivers - be sure to check in Windows Updates to see if a driver was updated prior to this occurring. This could also be caused by a loose card or cable and even a weak power supply.
That error 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.
Check these :
Error message when you try to resume a Windows 7-based or a Windows Server 2008 R2-based
computer from hibernation: "Stop 0x0000009F"
http://support.microsoft.com/kb/977186
Stop error when you put a computer that is running Windows 7 or Windows Server 2008 R2 to
sleep or into hibernation, or when you restart the computer: "0x9F"
http://support.microsoft.com/kb/975599
"0x0000009F" Stop error message when a computer enters and resumes from hibernation in
Windows 7 or Windows Server 2008 R2
http://support.microsoft.com/kb/981848
This one is possible if BlueScreenView OR MyEventViewer (or EventViewer) shows the appropriate code.
Windows Kernel event ID 41 error in Windows 7 or in Windows Server 2008 R2: “The system has
rebooted without cleanly shutting down first”
http://support.microsoft.com/kb/2028504
And :
"Stop 0x9F" or "Stop 0xFE" error on a Windows 7-based or Windows Vista-based computer that
uses certain AMD USB EHCI host controllers