My 3D Coat version is 4.804 (DX64)
How to replicate my issue.
Fresh install.
Press END to set a hotkey, B, for the Brush Tool. Press Redefine on prompt.
Press END to set a hotkey, E, for the Eraser Tool. Press Redefine on prompt.
Press E to select Eraser, and then B to select Brush tool.
While Brush Tool is active, press B. For some reason this swaps me back to the Eraser Tool.
This happens with every tool. (e.g If clone tool was my last used tool, then pressing B would swap me to it instead)
I've tried this on different computers. My understanding here is that this isn't a bug but perhaps an overlooked consequence when sticky keys was introduced a few patches back.