Unity used to work perfectly for me. Now, every time I load it up it comes up with this:
What do I do? I've tryed re-installing it but it still wouldn't work.
If you go to your project folder, you'll see two directories, Assets and Library. The message is explicitly telling you to remove the file WindowPreferences, from the Library directory.
Assuming that is indeed the corrupt file, re-installing Unity won't help you, as the issue is not with Unity but with one of your project files.
Have you tried removing it?
You could move your project folders and in unity go to
edit -> Unity preferences -> show project wizard on start up
If you upgraded your OS check that you dont have compability set to windows 95 or something in unity3d.exe
LOL WTF IS UNITY ANYWAYS SOUNDS LIKE A NERD GAME