The best way to keep USB viruses from injecting themselves to your PC or laptop is to Disable the USB Autorun feature and I will teach you how to do it.

   1. Click the Start button, then Run and enter “gpedit.msc” without the quotes
   2. Go to Computer Configuration -> Administrative Templates -> System
   3. Scroll down to “Turn off Autoplay” and double click on it
   4. Click on the “Enabled” radio button, then for “Turn off Autoplay on” select “All drives”
                                   
                              OR
    Just keep holding Shift when u insert a USB disk? it cancels the autorun.