BBC's Rory Cellan-Jones looks at what caused the worldwide crash
Media playback is unsupported on your device

What caused the worldwide Blackberry crash?

It has been another frustrating day for the millions of Blackberry customers across the world who are unable to access the likes of BBM, email and the internet.

Users have taken to social-networking sites such as Twitter to vent their frustration.

Rory Cellan-Jones looks at what has caused the meltdown.