This seems to be a recent phenomenon. I noticed it first in Navisworks and then occasionally in Revit or AutoCAD. What is that you ask? Well it's hard to describe. When I use a command and then move my cursor away from it to do something else a tooltip appears for that previous command. In some cases I didn't use the command, merely my cursor was hovering over it before doing something else. It's weird.
I've tried disabling tooltips entirely but there doesn't appear to be a way to do that in Navisworks, or if it is possible I've not stumbled on to it yet. Similar for Revit and AutoCAD.
A practical very recent example, I used Refresh and after it completed I moved my cursor to the far right side of the screen to activate the Properties panel and the tool tip for Refresh appeared. The only way the tip will disappear is to move my cursor back over the tool. However in the fifteen or so minutes since that happened no tips have appeared no matter what I do. It is so weird and annoying.
Strange stuff, maybe it's just my PC...