Dark areas and shadows look like an oil spill in Develop Mode upon updating LR. Help!

[Jake35135035o5h4]

This has happened to me once before but I can't recall how I sorted this issue out. You'll be able to see in the Develop vs Library mode a huge difference in the darker areas looking heavily effected. Yes, the example image was already heavily edited but this is happening to photos I haven't even touched, but it's especially noticeable in darker images. 

Any help here would be appreciated!!

Thanks

[Rikk Flohr: Photography]

Model Year of your Mac?
Video Card?