Many Nikon D5100 owners who are using the Camera to take pictures using RAW format instead of JPEG are familiar with the following problem:
Windows and 3rd party application ( including old Versions of Nikon applications) will not open the RAW format files.
Though this issue can be a real pain, its solution is very simple:
In the Link below you can find Microsoft Camera Codec package, after installing that your RAW Format files produced by the Nikon D5100 would open as any other picture format.
Please share with us if this link helped you opening you Nikon D5100 RAW Format files in Comments below.