Searching on the net, this seems to be a common issue. I'm not able to plug any usb device without rebooting the mac. First thing i've found on the net, was that (most likely) the kernel and system.kext doesn't match.

I've checked, and indeed it didnt match.

System.kext
System Resource Pseudoextentsion, Apple Inc, 10.4.0

Kernel
Darwin Richie-Holzkens-Mac-Pro.local 10.0.0 Darwin Kernel Version 10.0.0: Mon Oct 12 04:06:05 AST 2009; anappirtrvh:xnu-1456.1.26/BUILD/obj/RELEASE_I386 i386


Now I want to fix this obviously, but how? How do I update my kernel without harming the computer as it is right now. I've been struggling to get it working. Right now, everything works (as far I know) except the USB.

Specs:
Mobo: Asus M2N-XE
CPU: AMD Phenom X4 9500 Quad Core
GPU: Asus Nvidia Geforce 8800GT 512mb
RAM: 2x 1GB OCZ XTC GOLD 800 Mhz DDR2