Switching off by itself

[saxophone]

My BB 8900 sometims just goes black and switches off by itself and other times the hour clock starts running as if rebooting
Please can someone tell me what the problem can be
Battery pulls have not helped

[vidukamark]

I had the same problem all of a sudden for the last two days. All I did was copy over the Street Hawk theme ( :D). After spending some time tweaking the settings - nothing helped. So tried removing the SD card and so far has not rebooted; been a day now - fingers crossed. Might have to check if your card is formatted or not.