In most cases this occurs when the memory is full. If the available memory is less then 2GB the LED will flash red indicating that the memory is getting close to full.
If you try to start a recording and there is not enough available memory the recording will not start. However, don't worry it is easy to transfer or delete videos to free up memory space. Check out the instructions below.
If the issue continues after you clear the memory, try factory reseting the device. In most cases the Factory Reset will put the device back into a default state and get everything working as normal.