Hi @horsky, sorry to hear about some of your unfortunate experience with the 4C. Unfortunately in a small number of cases, users can experience persistent issues in relation to calibration quality in certain regions of the screen, however there are a number of things you can try to improve the situation. For example, try to adjusting ambient lights levels in room in such a way that there are no strong source of Infrared lights from either open windows or strong spotlights near the eye tracker.
If it’s possible to test your tracker in a different room so test any difference, please try.
That being said, your stated issue with overheating on one side of the tracker and crashes seems quite unrelated and possibly more serious.. it’s always a good idea to ensure your motherboard BIOS and USB Chipset Drivers are fully updated as older versions have been known to cause connectivity issues. You might also try connecting a different USB port or via powered hub.
From the Tobii system tray icon, you can collect diagnostic data there which will contain within the logs perhaps some useful information. If you can cause (or wait) for another crash of the Tobii software and isolate the logs being produced and report them, that would also be useful. Thanks for your patience and hopefully we can isolate the problem for you quickly.