Disable screen saver on OS X 10.9
Deleting that wouldn't work. The only keys stored in that property list, by default, are:

njboot$ defaults read com.apple.screensaver
{
    askForPassword = 1;
    askForPasswordDelay = 900;
}


These keys are tied to: System Preferences &gt; Security &amp; Privacy &gt; General &gt; "Require Password 15 minutes (900/60) after sleep or screen saver begins."

You need to modify current host properties (saved in the "By Host" folder). To do so, open Terminal, and enter the following command at the command line prompt:

defaults -currentHost write com.apple.screensaver idleTime 0


Here's the result:

defaults -currentHost read com.apple.screensaver`

{
    CleanExit = YES;
    PrefsVersion = 100;
    idleTime = 0;
    moduleDict =     {
        displayName = "Computer Name";
        moduleName = "Computer Name";
        path = "/System/Library/Frameworks/ScreenSaver.framework/Resources/Computer Name.saver";
        type = 0;
    };
}


0 = never. Log out and log back in for changes to take effect. Once you log back in, you will notice under System Preferences &gt; Desktop &amp; Screen Saver &gt; Start After: Never is set. This will override setting it via System Preferences. You can test this by setting the screensaver time, logging out, and logging back in. It will still read never. If you wish to undo this command in the future:

defaults -currentHost delete com.apple.screensaver idleTime


Googling the issue revealed that a corrupted launch services database could be one possible cause, and rebuilding it may solve the underlying issue.