Christy,
Try these troubleshooting steps.
Generally, trying to repair the connection works. Try doing all three. There are also some advanced tools at the top of the utilities, although I think it would work only with a corrupted database.
If you actually look in your Amazing Charts folder on the main computer, can you see Codes.mdf and Codes.ldf?
If you can't see Codes.mdf, you probably aren't going to find it on that computer. But, you have a couple of options. You can either redownload to a different place and grab the Codes.mdf OR you have should have quite a few Codes files on all of the clients. Just copy and paste one in. That should work if you are only missing the one file.
Can't be too sure as I haven't played with V4 all that long. And, I have no idea why it would just disappear.
