I bought a new optical USB mouse. When I connect it to a USB port like normal it moves to quickly. It moves about four pixels at a time rather than one. Strange thing is, if I connect it to a PS/2 port through an adapter it behaves perfectly.

I have found that using xset to disable acceleration helps a little, but it is still not smooth through the USB port. Also, xset does not seem to affect how it behaves in games. One tick is almost a centimeter in the menus of Doom3.

I really want to use a USB port because I can chain it off of my keyboard which has 2 ports. I don't understand why it doesn't work the same for both USB and PS/2.

In your XF86Config file (or whatever equivalent) add an option to the input section:

Option "Resolution" "integer"

Where integer is by default like 300 in counts per inch. Bump it up or down as needed. Restart X after each change.

Actually, I already tried that. It doesn't seem to make a difference.

I'm having a similar problem.

I run an identical desktop system which is fine in terms of mouse movement. It has a PS/2 mouse and a USB mouse. Both are similar in their movement.

My laptop has a sensitive touchpad and an even worse USB mouse. The sensitivity is already set all the way down. Changing the resolution in xorg.conf does not seem to make any difference. I live with it but I would really like to find a solution to this issue.