You should either use try-catch blocks or check the existance of file at the starting point. You can find the use of try-catch block on google or MSDN site so i will not explain it here.
Use of file checking should do:
1) Open Project
2) in the event code write
if (File.Exists(filePath)){
Application.Run(new StartForm);
}
else
{
MessageBox.Show("File not found");
}
That should work out for you.
or you can do the same with try catch block.