I have been on several forums where members mentioned having problems with their SD Cards or cameras. I emailed Moultrie and this is the quick (3 day) response I received and I quote the following:
Use PNY, Sandisk, or Lexar SD cards. Don't use Ultra, Highspeed (HS), Optima or Micro Cards as they will not work in our cameras. Also make sure your card speed is a "2". This is found on the card or in a "C" on the card. If the card doesn't have this it should be ok to use. New cards out now have speeds (2,4,6,8,10).
Don't use a SD card that is too big for the camera: ex. don't use an 8 gig card in a camera that takes up to 4 gig. as the camera can not read a card that is too big for it.
Don't erase your SD card with anything but the camera that took the pictures: ex. your PC, another camera, or a card reader as doing so could cause the camera to lock up. Don't use a card that has been used in another camera as it could have a different format than our cameras. If this is the case with your card you will need to buy a new card. *By another camera, I presume they mean another brand of camera.
Only use Duracell or Energizer batteries.
I was happy with Moultries quick response and to receive this information which I wanted to pass on to help the forum members. Good luck.

i have 2 cards per camera,that way i can swap cards right at the cam. be in and out quicker. i use 4g cards as they are plenty big enough. i check cams every 7-10 days. have had 400 pics with plenty of room to spare on that size card

This is a great post, i've been looking around the net to see if i could find which sd card moultrie recommends. Thank you!

Thanks alot, good info to know.

Blessings......Pastorjim