When we invoke the WCF service from the client (another machine) for open any exe file into User Interactive mode, what happens it start the process of the exe with Process.start("exe"), but not shown into the User interactive mode. Reason is it always starts the process in Session 0, which is not an user interactive session. so for open any exe into User Interactive mode create a windows service and invoke/Start the windows service from WCF service. Please visit the following link for the same:
http://social.msdn.microsoft.com/Forums/en-US/netfxbcl/thread/0b4d79a8-abdb-4a76-ae3d-a425f21e6ec7
http://www.codeproject.com/KB/vista-security/SubvertingVistaUAC.aspx?msg=4101677#xx4101677xx
Write the code from this link into windows service and try to open any exe from client.
Thanks and Regards
Harsh