Sometimes when we plug in the pen drive to our computer, it automatically run the program that we never save the program to our pen drive and the program will install itself to our computer. The programs that install them self without permission could be malware and could infect our computer.

You can use Autorun Eater to detect if the pen drive contain autorun.inf. So you can decide letting the autorun runs or remove it.  You also can use Autorun Eater to Fix Task Manager, Fix RegEdit and Fix Folder Options.

You can download Autorun Eater from http://download.cnet.com/Autorun-Eater/3000-2239_4-10752777.html