How to bring up the "Windows cannot open this file" dialog?

Answer 1

This should do it:

System.Diagnostics.Process p = new System.Diagnostics.Process();
p.StartInfo.FileName = "rundll32.exe";
p.StartInfo.Arguments = "shell32.dll,OpenAs_RunDLL " + yourFileFullnameHere;

p.Start();

Answer 2

Process pr = new Process();

pr.StartInfo.FileName = fileTempPath;

pr.StartInfo.ErrorDialog = true;

pr.Start();