If you are trying to reinstall Windows 7 on your Sony Vaio PCG-71315L, you may have run into a common headache: missing drivers.
Where to Find Sony Vaio PCG-71315L Drivers for Windows 7 sony vaio pcg 71315l drivers for win7
Finding the correct drivers for a Sony VAIO PCG-71315L Go to product viewer dialog for this item. How to Find and Install Sony Vaio PCG-71315L
Solution: This is a power management conflict. Go to Device Manager > Bluetooth adapter > Properties > Power Management > Uncheck "Allow the computer to turn off this device". Also, ensure the Wireless switch (physical or Fn+F2) is ON. Bluetooth adapter >