I am the law!
I've been having major problems getting my mouse's tracking speed to stick. I can get it going fast enough by editing the .GlobalPreferences.plist, but after a few minutes of use, the speed drops back down to a crawl.

I was in the middle of doing a "pickup and putdown" routine to get accross my desktop when I got a Kernel Panic.

Machine is a Dual 500MHz G4 w/ 1GB of RAM. OSX10.1 and a Microsoft Intellipoint Explorer mouse.

Unresolved kernel trap(cpu 1): 0x400 - Inst access DAR=0x0314ad9e
Latest crash info for cpu 1:
Exception state (sv=0x14e62800)
PC=0x00000014; MSR=0x40009030; DAR=0x0314ad9e; DSISR=0x00002004;
LR=0x14f13824; R1=0x10853cd0; XCP=0x00000010 (0x400 - Inst access)
0x14f137ec 0x14c4a7c8 0x14c4a66c 0x0003dfe4 0x00033400
Kernel loadable modules in backtrace:
Kernel loadable module dependencies:
Proceding back via exception chain:
Exception state (sv=0x14e62800)
previously dumped as "latest" state. skipping...
Exception state (sv=0x14ba7000)
PC=0x00000000; MSR=0x0000d030; DAR=0x00000000; DSISR=0x00000000;
LR=0x00000000; R1=0x00000000; XCP=0x00000000; XCP=0x00000000 (Unknown)

Kernel version:
Darwin Kernel Version 1.4:
Sun Sep 9 15:39:59 PDT 2001; root:xnu/xnu-201.obj~1/RELEASE_PPC

Memory access exception (1,0,0)
the most frequent word appearing on crash descriptions worldwide must be <b>microsoft</b>.

Keyboard and Mouse not found
Press Any Key to reboot.
I've got an Intellimouse Explorer hooked up to a G4/400 PCI machine and I absolutely love it. Comfortable and I don't miss cleaning my balls (er, you know what I'm talking about) at all!

I, too, had problems getting the mouse speed to stick. After I would load certain programs with their own mouse drivers, like playing Quake or Tony Hawk, the mouse speed in the control panel would be back to a default speed. My solution: stop playing my damn games and do something productive!

Just wanted to let you know you're not alone. Might wanna check what programs you use that make the mouse go back to the default speed...
Quake is definatly one of them...but sometimes it just does it on its own [just did it to me]. And now I'm getting kernel panics! Just had another one a few minutes ago.
Weird... how did you install 10.1? I was having all sorts of weird errors when I updated 10.0.4 to 10.1... then I did the "Reformat and install" option under 10.1 and haven't had a single error -- stable as can be.

For example, my classic wouldn't launch! I have 9.2.1 on a separate partition for Classic, and after updating to 10.1, it kept telling me that those pesky extensions needed for Classic weren't installed, and when I chose to let it install them, it kept giving me an error stating that "An error has occurred trying to install blah blah blah." Classic was not functional for a while. Then, I did the "Reformat and install" for 10.1 and all is well...