Good idea, Patrick. It was indeed another program interfering. On the tiny chance someone has the same problem, it was a program called AltDrag, which I use to easily and quickly resize and move windows. It was specifically the "scroll inactive windows" setting. I unchecked that, and now the hot corners work perfectly.

Thanks!

Maybe a weird interaction with some other program? Could try with everything else shut down, including background applications?

I'm having trouble with MouseEvents on a Windows 8.1 x64 Dell laptop w/ Synaptics trackpad. After setting up the hot corners for MouseEvents, I can move my mouse to a set corner and trigger the action (e.g. window catalog). Afterwards, however, if I move to this or any other set corner, nothing happens.

I can open settings, un-check the MouseEvents plugin, then check it again and hit Apply, Once more, I can activate a corner...but only once, then they are all unresponsive.

Any ideas what might be going on?