Gimp opening offscreen

[Ofnuts]

Find your Gimp profile, and erase the sessionrc file (which is where Gimp keeps window positions between sessions), Gimp will start with default positions. If you feel a bit adventurous, instead of erasing it, you can edit it (it's a text file, but make sure your editor won't add an extension to it) and fix windows coordinates.

Once done, see this.