Sounds like you have a SD card reader on your computer instead of a SDHC card reader.
The older laptop computers came with SD card readers.
They will not read SDHC cards correctly.
Any store that sells digital cameras can sell you a SDHC card reader.
The price is usually between $10 and $20.
I'm using a Canon SX100 and have a Sandisk 8gb SDHC card. Long story short, I can view all of my pictures on my camera, but when I hook up the camera to the computer to transfer, most of them do, but some do not. Adobe photoshop elements 'opens' my pictures to transfer. It will show me thumbnails of my pictures and ask me to choose which ones to transfer. But there are some photos that are on the card that do not show up on the thumbnail preview. Am I doing something wrong or is it the card? I've tried to check the properties of a photo that is showing up against one that is not on the camera, and I don't see a difference.
I appreciate any suggestions you have. Thanks