I have been having trouble with usb not working unless I boot into safe mode. In addition when i tried to mount dmg files I got a kernel panic.

here is the solution I found.

In general you need to change the following kext's

For usb look for the kext's from slice
IOUSBMassStorageClass.kext
IOUSBFamily.kext

For the dmg problem you need to use the seatbelt.kext from 10.5.5

I am still having to boot up using -v -f