I have been using a Logitech Marbleman USB trackball for several years. Lately, it has developed an odd habit with my Ubuntu 12.04.5 LTS x86_64 system: if the trackball cursor does not get moved for about 30 seconds, it gets "stuck" where it is. When I move the ball, the cursor stays where it is on the screen for several seconds before it will start to respond. If I click a button, the cursor starts responding again normally. It is as if the driver doesn't notice the ball being moved right away.

I have not seen any other messages about this, which makes me wonder if it is peculiar to my particular system.