Hello everyone. I just purchased my first Mac. It's an iMac desktop. Here is the main issue I'm having: transferring files. This is what I do: Connect my external drive and SD card to the Mac. Open both in Finder. Click on a file from my SD card and drag it to the external drive. Here's what happens: It won't move the file. I get a "no" sign. I have also tried opening one in Finder and the other in Bridge, but I cannot transfer files that way, either. I can transfer files to the Mac hard drive. But I cannot transfer those files to the external drive, which is where I want them. To further complicate things, when I use my laptop (not a Mac) to transfer files from the SD card to the external drive, I cannot save those files as new files on my Mac. For instance, I transferred a file from my SD card to my external drive on a PC laptop. I connected that external drive to my Mac. I opened one of those files in photoshop. I altered the image and clicked "Save." I was given an error that said the file was not writeable. However, when I open that same file on the SD card, it's original location, I'm able to alter it in photoshop and save it with no trouble. This is a bit of a hassle for me. It means that I must create files on my SD cards, that I cannot transfer these files to an external drive unless I use a laptop, and I cannot alter images in a program that are saved on the external drive. I sure hope someone can help me figure this out. Thanks in advance!