The Asus ep121 touchscreen is a two-finger (at the time) eGalax multitouch screen 0xeef:0xa001. It should function as such but does not. The pointers movement and position are relative and not absolute, like a giant laptop touchpad. The hardware logs say it is a touchpad and load the Synaptics module for it.
Touching the screen causes a constant "mouse wheel up" issue as well as removing the ability to click even with a real mouse. The computer is unusable in this state until rebooted.
There are a number of workarounds for other eGalax touchscreens such as http://samiux.blogspot.com/2011/04/howto-ubuntu-1104-on-gigabyte-touchnote.html but nothing works.
These issues occur on 10.10, 11.04, and the 11.10 beta released sept. 1. In the 11.10 beta, blacklisting the synaptics module allows the touchscreen to work with absolute coordinates but bad calibration. It also registers a constant "left mouse button pressed" event after being touched.