Memory card not showing photos

Hello,

I have a sony camera and a sony memory card. I could see the photos in my camera but as soon as I put the card into the laptop to transfer the photos, it shows that there are no photos.....and that the card space is free...then when I put back the card in camera..the camera also says that there are no images!!

This is second time this has happened..the last time (about a week back)..same thing happened with sandisk memory card. I thought maybe changing the card would solve the problem! The last time I had to download a free recovery software and recover the photos (which took a lot of time!! - dont want to do that again!)..I assume there is some virus in my laptop or memory card...Can someone advise how to rectify this?

Thanks,

Ujjwal

Could someone pls. help??