Mouse stuck in top left corner of screen (spinning in circles)

[Romulator]

If I recall correctly, this problem is related to gaming controllers. Do you have any joysticks or gaming controls plugged into your computer? If so, try removing them and seeing if the problem persists.

Edit: Just realised you said "mouse stuck". You can still try the above method if you are able, but it may not work.
If you run the game in windowed mode, can you look freely?