Hello everyone, my MacBook is showing a strange behaviour, which I couldn't find solutions for yet. Therefore I registered here, also my english isn't the best. I hope you will excuse that =) After two years without any problems my MBP (13" mid 2012, Mavericks 10.9.4, HDD replaced with SSD 6 months ago) suddenly won't boot anymore from the SSD and just displayed the "forbidden" sign after the start. Windows on bootcamp-partition displayed disk read error... After several tries (PRAM-Reset, Internet Recovery, formating SSD,...) I restored the system from Timemachine to the original HDD and the SSD. But the problem isn't solved at all. After that, I could boot and work normally from the SSD attached external via USB 3 BUT: if i put the SSD in the MBP (SATA) it won't boot and shows the "forbidden" sign again. If I start from the external attached HDD, the SATA connected SSD shows up in Finder and I have normal write and read access to it without problems. The HDD works fine with the internal SATA-connector. SMART-Status from the SSD is normal and all partions on it show up normally when booting with pressed option-key. But i can't start neither the OS X partition nor the recovery partition on the SSD. I have no idea, why the MBP works fine with the SSD via USB and won't start from it when connected to SATA. Any hints and solution are welcome. Thanks in advance!