Error while using system.diagnostics.process

You can't add threads directly to a listview - ProcessThread does n't override ToString, so all you would get is

System.Diagnostics.ProcessThread

for each one.
And you can't do it that way anyway!

For Each p As Process In Process.GetProcessesByName(Form1.TextBox1.Text)
	Console.WriteLine(p)
	For Each pt As ProcessThread In p.Threads
		Console.WriteLine("   {0}", pt)
	Next
Next

Will at least give you some code that works as a starter!