I have discovered the same problem with my DSC-F717.

My camera has been safely locked-away in a cupboard for three months. This afternoon I took it out to take some pics and I have a black screen on both the LCD as well as the EVF. Everything else works fine, just not able to take pics. Saw that Sony has acknowledged the problem here: http://esupport.sony.com/perl/news-item.pl?mdl=DSCF717&news_id=95 Just sent an e-mail to Sony Asia Pacific to see what they have to say about it. Thanks to you guys, I found very quickly that I am not the only one with this sudden failure.

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