have you tried with an another memory card by any chance? Is the behaviour the same? Asha 302 should in principle support SD memory cards up to 32GB in size. It would be also good to make sure you have the latest device software installed on your phone (which is SW version 14.53). You can check the current SW version of your device by dialing *#0000#. If the SW is out of date, one should use Nokia Suite to update the device, as this specific update is not currently available as Over-The-Air update.
I too am facing the same issue. I purchased the Nokia Asha 302, yesterday. The camera just hangs after listening to music, or after sending a few messages.
Even if I save the image on the internal memory also it hangs.
I have the latest S/W update. It is still occuring. I need some help on this.