I only take screenshots on this system when setting up new tables, not videos at all.
I consider a blocking of buttons or the joystick to be completely out of the question, especially as the errors described never occur when I use VPX without PinballX. This also doesn't really fit with the power failure in the Slingshots. I have tried your Notepad suggestion. Everything works fine. I use the keyboard encoder I-Pac 2 in conjunction with the configuration program WinIPac.exe, but no other tools.
What is really annoying is the lack of reproducibility of the bugs: the errors suddenly appear, whereupon I close and restart the table in question and everything runs fine again. As I said, the blocking of the fins occurs every now and then and has done so since I started using PinballX; only the slingshot thing is new.