Allow Multiple Instances (allow more than one instance of the player to run at the same time)
By default, Zoom Player will only run once. Trying to run Zoom Player again will just bring focus to the previously running instance. Enabling multiple instances enables you to run more than one copy Zoom Player at once. A side-effect of this is that trying to open a new file from an external source (double clicking in explorer for example) will open a new instance of Zoom Player instead of loading the new content in the previously open instance.

Zoom Player provides other ways to run multiple instances, including separate configurations running at the same time, click here for more information.

Disable Screensaver and Monitor Powerdown when entering Fullscreen / Zoom mode
The Windows Screensaver and Power Management features can activate the windows screen saver or turn off your monitor as you are watching videos or listening to music. This happens because you are not giving the computer any input (clicking the keyboard/moving the mouse). Zoom Player can automatically disable the windows screen saver and monitor powerdown while it's in fullscreen/zoom mode to resolve this issue.

Disable CD / DVD Auto-Run (prevents applications on the disc from auto-starting)
Zoom Player can disable a CD's or DVD's Auto-Run capability (some CD/DVD discs can automatically run an application when they are inserted for the first time). Having a disc auto-run an application can be problematic when all you want to do is play the disc's content. Zoom Player must be in-focus for this feature to work.

Forcibly hide the Windows Taskbar in Fullscreen / Zoom mode (can cause focus issues)
In very rare circumstances, you may want to hide the windows taskbar when playing fullscreen video. Please note that windows doesn't react too well when you hide its task bar (it can cause problems switching between windows later on, until you reboot).

Show "Places" in Open / Save Dialogs
When opening files using the Open function, you are promoted with the windows standard open dialog. There are two variants to this dialog, one showing a "Places" box and another with only the file list. Unchecking this setting will show the open dialog with only the file listing.

Show currently playing title on the Task Bar button
When enabled, Zoom Player will show the currently playing file name on the task bar button.

Enable External Control Message Server (required by some third party applications)
Some applications may need to communication with Zoom Player through the Microsoft "SendMessage" API. This checkbox controls whether you allow third party applications access (or not).

Save configuration to a local file (instead of the Windows Registry, may slightly slow initial load)
When enabled, Zoom Player will save its configuration data to a file ("zplayer.local" in the Zoom Player program directory) instead of to the System Registry. This can slightly slow down Zoom Player's loading (under 1 second), but makes it easier to run different configurations of Zoom Player in different directories and to backup/migrate Zoom Player.

Blank Secondary Monitors while in Fullscreen / Zoom mode
Enabling this setting allows you to blank-out any non-playing monitors while Zoom Player is playing in fullscreen/zoom mode. This is especially useful when playing from a laptop to an external TV/Monitor and having the Laptop's monitor blanked out and not acting as an distracting light source.

Internal Screen Saver should not Max the CPU
Zoom Player's internal screen saver is procedural (mathematically calculated in real time), enabling this setting ensures that the screen saver takes very little CPU power, but it will not be as smooth/appealing.

Allow the Internal Screen Saver to be used when playing Audio files
By default, the internal screen saver is not activated when playing audio files. This setting instructs Zoom Player that the screen saver should be active for audio files as well.

Use Internal Screen Saver (seconds)
Since Zoom Player disables the windows screen saver, Zoom Player implements an Internal Screen Saver. Unlike Window's screen saver, Zoom Player's internal screen saver only activates when nothing is playing (media is paused, DVD in menu, etc).

Enable External TCP Control (port)
Beyond supporting microsoft's "SendMessage" API. Zoom Player provides a very powerful Communication and Control API that works through TCP/IP (the underlying protocol used by the internet itself). This API allows you to communicate and control with Zoom Player externally (even over the internet). For more information on Zoom Player's Communication and Control API, visit the Third Party Enhancements sub-forum.

CD / DVD Drive
The specified DVD drive is the first drive Zoom Player will look for when you press play in DVD mode. If no DVD is found on this drive, Zoom Player will quickly scan other drives for DVD content.

Fullscreen / Zoom to Monitor
When switching to fullscreen/zoom mode, this setting allows you to select which monitor Zoom Player should switch to.

Player Thread Priority
Each windows application has a Thread Priority. The thread priority lets windows know which application should have more (or less) CPU power available to it. Think of it as a pie, each application is a slice of the pie and the thread priority is the size of the slice. It is not recommended to use a thread priority greater than "Above Normal" or it may have an impact on system stability (especially when loading badly corrupted media files). You should set the Thread Priority to "Above Normal" in situations where you're running applications in the background and you don't want your media playback experience to suffer (dropped frames, audio going out of synch, etc).