Okie, open up options on the login screen. Click over to the video tab, and change the "Rendering Subsystem" to the option that it's NOT currently set to.
If this makes it worse instead of better, go to the FeralHeart folder in Computer>Local Disk>FeralHeart. Scroll down to "unins000" and uninstall. (**BUT remember to backup any maps you have in your exports folder first!**) After uninstalling, delete the FH folder completely and then reinstall.
One of the two options above should fix your problem. If not, try updating your graphics card.