Your system's memory configuration has changed since it entered hibernation.

I got this above error while starting the PC. I am using windows 7 OS,

"Your system's memory configuration has changed since it entered hibernation. If you proceed, the data needed to resume from hibernation will be lost. To preserve this data, turn off the system power. If the power was interupted during the starup, choose start windows normally.
(Use the arrow keys to highlight your choice.)"

Solution:

• May be due to hardware change in your computer. 
• Fix the RAM properly and try rebooting the system. if still have a problem may be your RAM stick damaged.

You only lose your didn't saved data, Just select windows starts normally option and run the PC.