Compaq Presario SR2177CL mmc/sd slot

I was trying to retrieve pictures from a memory card from my
digital camera, and I put the memory card in the slot, the green light
lit up and nothing happened. I took the memory card out and the green
light stayed on, the computer is only about 5 months old. The green
light will not go out even when I reboot the computer, I would welcome
any suggestions as to what the problem might be. Also when I put the
card in the slot, should something pop up on the screen and ask me what
action I would like to take? Cause nothing like that happened. And one
finale question is there a way to access the mmc/sd slot through windows
explorer? By the way I am running windows Vista.

Thanks