screen goes black, and device restarts by itself.

[samryp]

I am using xperia t2 ultra dual.
My problem is that device's screen goes black 3-4 times in a day..
I mean the device is on, I can feel the vibration on touching the phone, even I receive call but nothing is displayed on the screen..
Then I have to restart the cell by holding volume up and down button and the power button together..
One more thing
The device also restart 3-4 times a day by itself..
I am frustrated.. Please help...

[kugar]

this is caused by a faulty memory card .....i removed the memory card and solved the problem and formatted ait and reinserted it...all solved