Hey ladies, I really need some camera help.

I own a Nikon D3100 DSLR Camera. I love it.

HOWEVER, recently I haven't been able to get any of my photos off it.

I have a 2008 Macbook and it doesn't have a SD card slot so I usually just tether it in with the USB cord. All of a sudden that stopped working. I thought it was the cord but even after getting a new one it still didn't work. It doesn't register that my camera is even tethered in.

My husband has a HP laptop and it does have an SD card slot so I took the SD card out and tried it in there. It worked! So, I got all my photos off the camera that I wanted and took the SD card out.

Later, I put it back into my husbands computer to get some more photos off the camera and bam. It didn't work. It doesn't even register that there is an SD card inserted into the slot.

This camera shouldn't be having these kinds of problems. I haven't had it that long and it was brand new when I got it. I will admit that I'm not great about "safety removal" of devices, and never have been, but I've also never had any problems before with any of my previous cameras.

Can anyone shed some light on this situation for me? Or do I need to take it to a camera store and have them look at it?