Blender 2.82 ignoring MOST mouse input

My 2.82 has started ignoring MOST mouse input, although it still reacts to cursor placement. Fields and menus still highlight as the cursor passes over them, but it is not possible to select most items, and MMB navigation is not working.

Relaunching and/or reboot+relaunch doesn’t seem to help, although the mouse is functioning in all other software. B is also ignoring keyboard navigation, such as numpad “6” or “7”.

…aaaand, it just crashed on CTRL+S.

Since this behavior is persisting across reboots, I wonder if there’s a FILE that is causing the issue, and if deleting that file will cure this.