SDHC Card is not displaying on PC, what to do?

Hello guys,
I have a Sony DSC W320 Digi-cam. I use a Sony 4GB SDHC card to store my pictures. It was working well and fine, but recently it has started troubling me. When I am inserting the card into my laptop, it is not displaying anything, the Removable disk was supposed to appear, but it is not! I thought the problem is with my laptop’s card reader, but the same is happening with other laptops also.
Now I need a quick help on this, I have some really very important pictures, and i dont wanna loose them. The card is working fine with my camera, I can see the pictures also.
Please suggest me some good ideas.
Thanks.