First thing is to figure out if it's the card, the camera, or the computer. Try plugging the camera into another computer. If it doesn't work on another computer then get a another card, format it in the camera and see if that works (a small capacity cards are quite inexpensive and are a handy way to transfer pictures). Of course you don't want to reformat your existing card unless you are very sure that the card is the problem because reformatting will destroy all the pictures you are trying to save.

If we're getting up a betting pool here, I'll bet the eventual fix will be to reformat the card. Good luck.
- Phil