It sounds like you found the
Cursor/Inventory selection bug...maybe? topic...
Did you try windowed mode?
Did you try resetting the other mouse options in Windows?
If you have a controller to test with, do you have any issues with the controller UI?
Do you have this problem with the Classic version of the game (if it happens frequently enough that testing is feasible)?
Are you shutting down all non-essential programs before starting the game, especially any graphics or chat programs that add an overlay?
Try doing a clean boot and then test the game. Click Start, or hit WinKey-R, type in msconfig and hit enter; in the General tab, click Selective Startup, uncheck Load startup items (if required) and leave Load system services and Use original boot configuration options checked. Next, click on the Services tab, check the box to Hide all Microsoft services, then click the Disable All button (maybe make a note of which are currently enabled/disabled), then click OK and reboot the computer.
Run msconfig again to switch back to the normal boot configuration.
In the '..\SteamApps\common\Divinity Original Sin 2\DefEd\bin' folder (or '..\Divinity Original Sin 2\Classic' for the original release), try right clicking the EoCApp.exe game executable, select Properties, switch to the Compatibility tab and check off the 'Override high DPI scaling behavior' option (set it to Application), maybe run as administrator and disable fullscreen optimization, and set a Win 7 or 8 compatibility mode.
Please email supportdos2@larian.com with link to this topics and a dxdiag report (WinKey-R, type in dxdiag and hit enter, then when it finishes loading click on the 'Save All Information...' button and save the report somewhere handy).
