On pgAdminIII 1.12.0 beta 1, I've been having this happen really frequently. One table I can't even edit--as soon as I type a single character in a column to make a new row, it crash-vanishes every time. Actually, it does an odd thing before vanishing, creating a set of horizontal and vertical scrollbars in the upper-left of the data grid (over top the data), freezes a couple seconds, then all the pgAdmin windows disappear.
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