ehshell.exe is a process belonging to the Microsoft Media Center and provides most functionality for the Microsoft Media Center. "This program is a non-essential process, but should not be terminated unless suspected to be causing problems. "
Non-system processes like ehshell.exe originate from software you installed on your system. Since most applications store data in your system's registry, it is likely that over time your registry suffers fragmentation and accumulates invalid entries which can affect your PC's performance. It is recommended that you check your registry to identify slowdown issues