http://psp.1up.com/do/newsStory?cId=3138532
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Sony has announced that a flaw in the PSP's manufacturing process that could lead to stuck square buttons has been resolved. According to PlayStation.jp's support section, the molding of the casing was the problem. Units manufactured in the new year no longer suffer from the problem, thanks to new procedures; older units that did were under warranty and have been repaired or replaced by Sony.
Sony has previously claimed that only 0.6% of the units shipped last year were repaired for square button problems. Anecdotal evidence suggests the problem is more widespread. Either way, it's now resolved, which means that statistics are largely moot.
Original topic was locked.