Marty, haven't had the problem myself. dissappointed that Adobe doesn't seem to publish any listing of their error codes, at least none that I could find.
You didn't explain your particular setup or where the file was located, but I found the following links on Adobe that might be of use. Of course, they recommend working with the file on the local machine, so if you are working from a network or external usb/firewire drive, that could be a possible problem especially if it's a large file.
Also, don't trust the preview, I know at least in Photoshop that it doesn't have to represent the actual image, that's how some people have taken the preview to a small image to reveal what the full image used to be.
Troubleshoot damaged files (Illustrator CS, CS2)
Illustrator, networks, and removable media