Hi @lore, sorry to hear about your issues. In this instance, it sounds like there may be a hardware firmware fault here.
Assuming you have already tried different USB port and ensuring that BIOS and USB Chipset Drivers are fully updated, please kindly get in touch with Tobii Support directly @ https://help.tobii.com/hc/en-us/requests/new
Where you can send them diagnostic files of the eye tracker for analysis to determine whether or not your tracker needs replacing. Many thanks.