Just tried that, Same thing.
The weird part is that it's only for storage devices, i use an external keyboard/mouse and that seems to be just fine, if i try an iPod or a USB stick or anything of that sort, the screen fills up in a gray shade and says - you must restart your computer ... etc.
I also have similar results. I did NOT notice it with USB sticks, but my external MBA SuperDrive does not work with the modified kexts as I stated in my post #56.
For those who do not have keyboard and mouse in safe mode, I have also gone thorough that and had to reinstall from the OS DVD's. Notice (jamestemroot), all my data remained unchanged (I do remember some minor change, but I cannot recall what it was, but it was very minor) and my keyboard and mouse started to work. I was then able to run the command lines in my previous posts without a problem.
dnguyen, I do not have a solution if you don't have access to the DVD's except try to download them... they're on the internet... torrents etc.
Oh... wait... maybe I do... you can try screen sharing (or maybe remote login or remote management) from another computer. Of-course, you have to have enabled one of these to be able to reach your computer.
Please check my note half way down my post #63 where I suggest to keep copies of old, new, and modified files in different folders in order to be able to return to an unmodified state after you're done with the jailbreak/unlock. This, in order to avoid the little incompatibilities with the modified kexts such as with my SuperDrive and other USB devices.
I have uploaded my versions of the kexts:
http://rapidshare.com/files/179137533/DFU_fix_IOUSBFamily.zip.html
Inside the zip are a text file with the command lines (change "Dotan" to your own username) and three folders with the different kexts (see my post #63).
VERY IMPORTANT: These files are for an early 2008 Macbook Air OS X 10.5.5 (folder named "old") and a Late 2008 Macbook Air OS X 10.5.5 * (folder named "new"). The third file is the NEW kext with the OLD kexts inside it.
*The new MBA came with OS X 10.5.5 which had the DFU issue even before 10.5.6 was released to the other macs.
I do NOT take responsibility for anything that you might try with these files. It does work for me and I am able to be recognized in DFU. Again, I stress, these are for a NEW MBA and I have not tried them on any other device.
Happy New 2009, and hope it helps some of you.