Published a ClickOnce application and it keeps resetting its settings

Question

I have deployed this application using Visual Studio 2010's Publish feature; it needs to save a few user settings (such as database connection information) and there is this particular computer that somehow keeps resetting the application's settings. The part that puzzles me the most is that I have not been able to figure out under what circumstances or the reason why this happens. I know the settings are getting set properly because the application has worked just fine on 6 or 7 other computers.

What could be erasing the application's settings? Alternatively, what would you suggest I use to store those settings? An encrypted file?

EDIT: I am using the default application settings. They are defined in the app.config file. They can be accessed using Properties.Settings.Default.propertyName

Answer 1

For anyone who runs into this problem: Check if you have an unconditional

Properties.Settings.Default.Upgrade();

in your code. In a ClickOnce installation with multiple versions, this statement copies the user settings from a previous version and overwrites any settings that were saved in the last session. The correct pattern is:

if (Properties.Settings.Default.UpgradeRequired)
{
    Properties.Settings.Default.Upgrade();
    Properties.Settings.Default.UpgradeRequired = false;
    Properties.Settings.Default.Save();
}

where UpgradeRequired is a setting that defaults to true.