I do not know if anyone else has had this problem, but it can occur and has occurred to me already. I've just spent one full hour and a half restoring my computer after installing the patch for enabling DFU on 10.5.6. This replaces two kext files that are associated with the USB. After installing the patch, my system worked fine for a good amount of time, don't remember how long exactly. After that, ALL USB ports stopped working! If you have already installed, you will run into this problem, Leopard will find out that those files were tampered with and somehow disable them. This has already happened to me. If your still going to attempt this, go at your own risk!