Look at the latch that keeps the drawer closed. Sometimes, if you open a drawer too slowly, the latch will not open all the way as it is supposed to, but will open part way and then close with the drawer open. Take a small screwdriver and carefull open the latch and then the drawer will close all the way and (hopefully) stay closed. Open another drawer quickly and look at the latch and you will see what I mean.
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