Sorry to hear you're experiencing troubles. This isn't something that any of my Windows testers reported before release, but it's something I'd like to look into further. Would you mind emailing through some more information on your system (system specs, OS version, graphics driver version, etc.) and a copy of the game's logs from a play session where this has occurred to support @ jbushproductions.com? The logs folder can be found by selecting the "Show User Folder" option in the Settings menu.
Does this happen when the game is running in a window, or only when it's fullscreen?