hello All, I purchased in september 2012 an ultrabook Sony VAIO T13, I7, 8GB RAM, 256 GB SSD and I experienced with same problem, it happened sometime, after 2:3 days: while I'm in internet it happens suddently: a black screen with the message Operating system not found". I have to hold down the power button to shutdown and after the VAIo restart again normaly. I contacted the Italy SONY Support but they only recommended to restore the early status of machine at the purchasing time because it is a windows 7 issue. I tried 5 time the restoring, a experienced computer center tried 1 time, the SONY Customer support tried 1 time the restoring. But the issue appears always. I claimed to SONY Support and they declaree that it is a Sw (Windows 7) issue.
I finished my tentatives to have a valid support by SONY Italy. Do You know any International Quality office/ Customer office of Sony that can help me?