Maybe you are out of memory
To gauge available memory on a Kindle 3 (also known as Kindle Keyboard), navigate to Settings > Device Options > Storage Management. This will display how much storage is currently being used and how much is still free. The Kindle 3 typically has 4GB of internal storage.
Here's a more detailed breakdown:
# ***Access Settings:*** From the Home screen, press the Menu button. Then, select "Settings".
# ***Navigate to Device Options:*** Find and select "Device Options".
# ***Check Storage:*** Select "Storage Management" to view the storage usage information.
# ***View Available Memory:*** The screen will show how much storage is used and how much is free.