I have Slackware 4.2 on basically a fresh install with KDE. The desktop wouldn't load up at all, and since it wasn't recognizing my wifi adapter either, I got the package files and dependencies for my graphics driver installed from a USB stick via command line. Fun.
After doing that, My mouse doesn't work at all. The pointer shows up, but moving the mouse doesn't do anything.
I'm using the nvidia-legacy-304 driver for the Nvidia 6150SE graphics. I driver issues because of this, but never mouse issues before.
Keep in mind I don't have internet access on this computer, the router is too far away to connect an ethernet cable. I'm still fairly new to Linux and especially Slackware, please help me.
Edit: Getting DOZENS of: usb 1-3 device descriptor read/8(or 64), error -110 On boot

What packages and dependencies did you get and from where? Depending on how the packages were built, it could easily be causing your problems.

First, the easy question, have you tried another mouse or another USB port on the computer? Next, can you get us your /var/log/Xorg.0.log file? This may help diagnose what's going on.