Compact Flash Card Connected but not Showing any Data

I have a Sony Digital Camera which I used to take many pictures.
Recently I got in a problem.
I tried to connect the compact flash drive in to my computer and take all the pictures.
It's seems that the drive is showing in My Computer but when I open the drive the pictures inside the compact flash card doesn't show up.
I tried to connect several times but same result. Is it because virus?
My computer has Norton Internet Security installed and updated.
It's really important for me as there are many beautiful pictures in that flash compact drive.
Please help me.
