Pinballx set mouse pointer to a small dot, so you won't see it.
This can be changed in settings.exe
PinballX sets the startup in the users startup folder. Maybe somethong went wrong there.
You can always try by renaming pinballx.exe to pinballx_2.exe so it wont start.
Maybe the person who sold you the cab did something for loading pinballx as well.
You say settings.exe doesn't work? Mine is launching most of the time minimized and I need to right click on the startmenu to open it.
Don't uninstall it, but just try to fix your issue.