USB Devices like i-pod,pen drives e.t.c; brings viruses/worms which are bad since it disables a lot of features as well as it ruins memory the slows down the whole thing. It disables much of the removal process like Windows RegEdit.exe, MsConfig.exe and also TaskMan.exe. Variations of these also disables your keyboard during normal booting, floods your disk with virus files in the root directory and also the windows directory and some also floods your directory with Folder looking icons that is an executable..
So here are some tips in avoiding this: