Help me fix a disk read error that has occured on my home computer?

Help!
I downloaded some pictures from my Kodak digital camera (about 20). I took them from my 'My Photos' to a desktop folder. Then tried to download them to an e-mail on my AOL account to send to a friend. For some reason, the photos were trying to show individually in the e-mail as opposed to an attachement. It was taking forever and the system seemed to freeze (after about 10 - 15 minutes). While the cursor would move, nothing else would respond. I tried to close the process of downloading. I tried to close AOL. I tried to mimize the whole thing. Nothing worked. Finally, I pushed and held the 'On - Off' button till the computer shut down. I waited a few minutes and tried to start the computer again. All that I am getting on the screen is: "A disk read error has occured. Press Crtl+Del+Alt to restart." I do this and the computer goes dark for 2 or 3 seconds and the 'Gateway' (brandname) insignia comes up as it usually does. However, shortly thereafter, it goes back to the "Disk read error" message.
What can I do?