I am using a moderately decent computer running Ubuntu, and am also using a USB tablet and a USB keyboard. Might this have something to do with the problem?
EDIT: Here are some screenshots... they are in chronological order. After dieing or starting the game, I end up in the upper-right corner, as shown in screenshot 1. I then click rapidly many times in a second, allowing me to move to the lower-left a little ways, as shown in screenshot 2. But if I stop frantically clicking, I immediately return back to the upper-right corner, as shown in screenshot 3. This is very hard, seeing as how I am unable to actually attack anything without returning back to the starting point...


