You can try some basic trouble shooting such as resetting the SMC and resetting the PRAM, restarting in Safe Mode to clean some caches. However IMHO using a SD card reader is more reliable then connecting the connecting the camera directly to the computer.
SMC RESET
- Shut down the computer.
- Unplug the computer's power cord and all peripherals.
- Press and hold the power button for 5 seconds.
- Release the power button.
- Attach the computers power cable.
- Press the power button to turn on the computer.
PRAM RESET
- Shut down the computer.
- Locate the following keys on the keyboard: Command, Option, P, and R. You will need to hold these keys down simultaneously in step 4.
- Turn on the computer.
- Press and hold the Command-Option-P-R keys. You must press this key combination before the gray screen appears.
- Hold the keys down until the computer restarts and you hear the startup sound for the second time.
- Release the keys.
