First, make sure you are running the latest version of the LabQuest software. Versions 1.1.1 and newer include updates specifically to fix problems with LabQuests freezing. To update your LabQuest, see
     https://www.vernier.com/downloads/original-labquest-updates/

If you already have the latest version installed, here are a few tests to try to see if the problem is caused by a different issue:
1.Tap the home icon in the toolbar. If the button does not bring up the Home menu, the screen might need to be calibrated, or the screen may be defective. See:
     My original LabQuest screen is unresponsive or acts like I am tapping on the wrong spot.

2.If the Home menu comes up, try opening one of the other programs on LabQuest such as the stopwatch. Verify that the program works, then close it by tapping the X in the upper-right corner of the screen. If at this point LabQuest App does not redraw the screen correctly, use the Control Panel to reboot the LabQuest.

3.If the LabQuest gets stuck on the “System is rebooting” screen, you will need to perform a hard reset using the small reset button on the back of the unit. For detail on how to do this, see:
     How do I reboot or reset an original LabQuest?