I've been using Kubuntu for a few years now and had no trouble at all. Last week, I upgraded it to Kubuntu 12.04, and since then, have been having trouble with my optical mouse.
The mouse works fine as long as I am actively using the computer. If I pause for more than a short period of time (about a minute), the light on the mouse turns off, and it no longer responds to motion. If I click one of the mouse buttons, or push a key on the keyboard, the light turns back on and the mouse responds normally again.
The fact that the keyboard usage turns it back on seems to indicate that this is a power saving function. I have however disabled all power saving features, and continue to have this problem.
Any suggestions as to the cause/fix for this?