A difference between Lightroom and Photoshop is usually caused by a bad display profile. Sometimes different applications can react differently to a broken profile.
Is your monitor calibrated/profiled, and if so how, using what calibrator? If not, you may have installed a bogus manufacturer profile through Windows Update (that happens a lot).
Another possibility is a buggy video driver, although that's a lot less likely. To test, turn off Graphics Processor in PS Preferences > Performance.
