I think the only simple way to rename that file is to get the usbNetwork hack working so that you can SSH in and rename it.
I found the link. The driver you need is called the Windows Mobile Device Center (see http://www.mobileread.com/forums/sho...&postcount=228
Here is another possible way to rename the file back. WARNING: I'm not responsible if it doesn't work/goes wrong!
1. with debug mode on, type ~help in the search box -- you should see a list of the valid commands starting with ~. There should be one called ~exec.
2. In the search box, type:
~exec mv /mnt/us/usbnet/auto /mnt/us/usbnet/DISABLED_auto
3. Restart the Kindle (through the menu). This time it should start in normal USB mode, not usbNetwork mode.