How do you tell when another program is idle?

first off, the reason why someone would want to shutdown their computer when they are done downloading or installing something is I don't know.. maybe they have to go somewhere or their pulling a huge all nighter download and they want their PC to shutdown while their asleep.

Secondly, any type of download or installation. I got my program to list all of the processes that are running in a checklistbox. The design was that the user checks on the programs that they wish to monitor. If those processes closed or is "idle" then the program was supposed to shutdown the computer.

Thirdly, not all programs close when they are done installing, some stay open and say installation is complete and the user has to close it manually like video games, old software and non commercial applications.

Since there is no other way to do this then how do I check to see if the processes that the user selects from the checklistbox exited?

here is my code

namespace WindowsFormsApplication1
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}

int timer = 100;

bool restart;



Process[] pro = Process.GetProcesses();

private void Form1_Load(object sender, EventArgs e)
{



foreach (Process prolist in pro)
{
checkedListBox1.Items.Add(prolist.ProcessName);

}

}

private void button1_Click(object sender, EventArgs e)
{

MessageBox.Show("timer started");
timer1.Interval = timer;
timer1.Enabled = true;

timer1.Start();



}

private void timer1_Tick(object sender, EventArgs e)
{
if (timer1.Enabled == true)
{



timer = timer = -1;
}
if (timer == -1)
{

checkedListBox1.Refresh();

foreach (Process prolist in pro)
checkedListBox1.Items.Add(prolist.ProcessName);
{
if (listBox1.Items.Equals(listBox1.SelectedItems.Equals(0)))
{
MessageBox.Show("not found");

}


else
{
timer = 100;
}


}
}
}







private void button2_Click(object sender, EventArgs e)
{
timer1.Stop();
timer = 10;
MessageBox.Show("timer stopped");
}

private void button3_Click(object sender, EventArgs e)
{
checkedListBox1.Items.Clear();

Process[] pro = Process.GetProcesses();
foreach (Process prolist in pro)
{
checkedListBox1.Items.Add(prolist.ProcessName);
}
}

private void checkedListBox1_ItemCheck(object sender, ItemCheckEventArgs e)
{


listBox1.Items.Add(checkedListBox1.SelectedItem);




}
}
}