update... looks like this is a known issue with isochronous transfer frame scheduling problems?:

ok, now i think there's a memory leak in kinect.getRawDepth() . not sure if this happens on everyone's computer, but i'm seeing the leak even  when i just run the openkinect point cloud demo and getting the crash at about the same time interval (4h45m / 5 hrs).  i'm suspecting getRawDepth because i'm still seeing a memory leak when i comment out everything in the pointcloud demo except kinect.getRawDepth() .  figure this may be an issue with libfreenect?

so i had a question about how i solved this, so here's more detail:
>note: this solution is for a mac<

step 01: write some script into your processing .app to shut down at certain intervals
step 02: use cron to start up your standalone app

step 01:
insert this into draw() somewhere... i have it at the end of the loop

1.  int h = hour();
2.   int m = minute();
3.   int s = second();
4.   if ( (h == 3) && (m == 59) && (s == 58) ) {  //4am
5.     robby.keyPress(KeyEvent.VK_ESCAPE);
6.   }
7.   else if ( (h == 7) && (m == 59) && (s == 58) ) {  //8am
8.     robby.keyPress(KeyEvent.VK_ESCAPE);
9.   }
10. //etc...

i found i had errors quitting the standalone .app unless i used a robot to push the "esc" key.  you can learn more about using a robot from the processing wiki (which is where i got this portion of the code)... basically before setup you need

1. import java.awt.Robot;
2. import java.awt.AWTException;
3. import java.awt.event.InputEvent;
4. Robot robby;

and in setup() you need

1. try
2.   {
3.     robby = new Robot();
4.   }
5.   catch (AWTException e)
6.   {
7.     println("Robot class not supported by your system!");
8.     exit();
9.   }

i also added the kinect.quit() command to the escape key press because i found sometimes the kinect would crash even if kinect.quit() was in void stop()

1. void keyPressed() {
2.   switch(key) {
3.       case 27:  //keycode 27 = esc
4.           kinect.quit();
5.           super.stop();
6.           break;
7.    }
8. }

step 02: use cron to start up the program again
i used CronniX and two lines to start up the app at 4 and 8am should read something like

0      4      *      *      *      open /Users/Username/Desktop/yourP5app.app
0      8     *      *      *      open /Users/Username/Desktop/yourP5app.app

note, hours are 0-23, also remember to hit save in CronniX

in case anyone is having this issue, my solution was to switch to simple OpenNI (NITE wrapper for processing)... http://code.google.com/p/simple-openni/

don't seem to get this error with simple OpenNI... you lose some of the controls daniel's built into openkinect, but there are a number of nice new ones including skeletal tracking... and it seems to be the better option for running a sketch 4+ hours.