Notepad, if launched from an ASP.NET page will run under IIS' local user account, meaning that you won't see any windows or be able to communicate to the process from the account you're currently logged into. Windows will be displayed on the desktop associated with that account, not your desktop. The only indication you'll see is the process details in Task Manager, since all processes on the local system are displayed there, regardless of the user account they're running under.
还有,一般来说,只要没特殊配置,asp.net的程序肯定是用aspnet这个用户来启动的
执行asp.net的进程是aspnet_wp
NOTEPAD.EXE 的用户对象为0
http://expert.csdn.net/Expert/topic/2260/2260515.xml?temp=.6489221