I have a dialog box that may pop up when no one is at the monitor. I would like to display a countdown timer in the dialog box that lets the operator know that he/she has so many seconds to make a decision before the program moves forward. Is there a way to make the dialog box update while it is displayed? Do I have to make this a sub VI or is there an easier way? Any suggestions?

To the best of my knowledge, you won't be able to modify the built in dialog boxes to show a timer. This may actually be possible but I doubt it's easy. In my opinion, you will have to use a subvi and display the front panel when called. Arrange the front panel to visually look like the dialog box you want to appear, with a numeric indicator. Feed the timeout value into the subvi (this will allow you to decide when to exit the while loop). Use the "Tick Count (ms)" inside and outside the while loop. The one outside will mark the time at which the subvi was called. Subtracting the two will give the change in time (how long the subvi has been running in ms). You can subtract this number from the timeout value, and wire this to the numeric indicator. This will provide the effect of a countdown. If this value becomes less than zero, exit the while loop. Likewise, if the operator performs certain tasks, exit the while loop. On a side note, you can add a button to suspend the countdown. This will be useful if the operator gets to the screen with 2 seconds left.