FYI, X has a modular plugin system. Graphics is from an NVDIA plugin, but in this case the USB mouse disconnected (XInput). Following disconnect, the libinput was unloaded (there was no longer a device, so this is expected). Note that (as mentioned by @WayneWWW) libinput goes by udev events to determine what is present or missing, but it is out of the control of the X server to know this information (X is just doing what it was told to do by a udev event, and udev was probably just going by what it saw happen in USB). Now your real task is to figure out why udev dropped the mouse…if you can answer this, then you will know what is happening to the touch screen.
If there is a USB error, then probably at the same moment there would be a log note in “
dmesg” (e.g., if you “
tail -f” Xorg logs and “
dmesg --follow”, then both should print a message at the same moment).
There are a lot of reasons why a USB device might disconnect. One is from incorrect handling of a low power suspend mode, another is marginal signal quality (and
dmesg might distinguish among them). For signal quality there could be some intermittent noise source in the environment, or the traces could be poorly designed.