Having yesterday sorted out my small hand tools drawer, and sorting like-minded tools into chinese take-away plastic containers found this afternoon that the drawer woould not open.
After much cussing and swearing, in the style of M3OSN's email to the BRATS committee members, and hooking with carefully shaped bits of wire, it transpired that when the drawer was shut sharply, the inertia of the plastic trays made them slide forward so the head of a hammer dropped into the space behind, and the handle of the hammer pointed skywards and jammed behind the top lath at the front of the desk.
Moral : if you live in a mess, get use to it!