This problem is twofold, and seems quite strange too. First of all, I have a cheap, generic optical PS/2 wheel mouse (I think it is a PC Concepts brand or something). The first problem is, when I'm in X Window, whenever I move the mouse very slowly, it doesn't move the pointer at all. However, when I move the mouse over a certain speed, it works fine. This creates problems, though, when I'm trying to precisely select something and the mouse isn't already moving. The other problem is that if, say, Konqueror is rendering a web page, or something is updating its status, the mouse starts to jump around when I move it, like what happens when something is stressing the CPU so much that it has no time to render the mouse. I thought that the problem could be that the mouse is being software rendered, but then I checked to see that the Nvidia display driver renders the cursor using hardware by default. Also, before I reinstalled Slackware, the second problem didn't exist, but I don't think I did anything different. This problem is getting very frustrating, and I am out of ideas on how to fix it. Thanks for any help...

Well, the problem about the mouse being jumpy while doing two things at once or whatnot seemed to resolve itself(???). But I still have the problem about the thing sticking if I move it too slow. Could it be polling for the mouse position too slowly? I don't know...

Well, I don't know if anyone has the same problem as me, but it turns out that the way to fix this is simply to place

Option "Resolution" "256"

in /etc/X11/XF86Config under the core pointer section. It eliminates the mouse speed threshold problems.

I have the same jumpy mouse problem. How can I resolve it? I'm using Fedora Core 1.0 with a USB optical mouse.

First of all, as mentioned above, the
Option "Resolution" "256"
is always a good place to start. Also, I have discovered that if you replace the "256" with "512" it sometimes helps even more. If this does not help at all, the only two other things that I can think of are:
a) Your USB mouse simply can't put out movement data fast enough for some odd reason
b) Linux doesn't like your mouse model (btw, I think there are a few of extra options that need to be set in XF86Config for Logitec mice, but I don't know the specifics)
c) Your window manager's acceleration settings are all screwed up.

Hope this helps!