Microsoft Remote Desktop Connection tool – MSTSC.EXE
Mstsc.exe is the Microsoft Remote Desktop Connection tool. This command line utility creates connections to terminal servers or other remote computers, edits an existing Remote Desktop Connection (.rdp) configuration file, and migrates legacy connection files that were created with Client Connection Manager to new .rdp connection files.
More information can be found at http://technet2.microsoft.com/WindowsServer/en/Library/f47ce263-f72e-469d-bf14-6605b7f4cce51033.mspx?mfr=true.
This is a legitimate file. But if you have no idea why it's running on your system, you may want to stop it using WinPatrol.
Safe
Microsoft