Application says network drive doesn't exist, but found using OpenFileDialog

Question

I have made a little app that's running on a Win7-PC. All it does, is to check the content of a network drive at 1:00 O'clock in the morning (and compare it to a folder on its local hard drive), and if there´s differences, copy the differences to this folder.

The problem is, sometimes it can not find the network drive.

When the app starts up, the network drive is found using a button on the app which starts OpenFileDialog, and the resulting drive letter is put into a textbox beside the button. From that point it should just run by itself. The PC is never turned off.

When it says the network drive can not be found, I can manually press the button on the very same app, select the drive in the OpenFileDialog (the drive letter never changes), and the app will run flawless in a couple of days. Then the problem occurs again.

The question is: Why can the network drive be accessed through the OpenFileDialog on my app, but my app can not?

My app start the copy-process using this function (called with "Y:\") to determine whether the drive is present or not:

    public bool fn_drive_exists(string par_string)
    {
        DirectoryInfo di_dir = new DirectoryInfo(par_string);
        if (di_dir.Exists)
        {
            return true;
        }

        return false;
    }

...and sometimes it returns a False, until I "wake it up" using the OpenFileDialog.

What does OpenFileDialog do, that my app do not?

Answer 1

According to this SO post, the problem should be gone if you use UNC path instead of mapped network drive.