>I've added a new field to an existing table, and am trying to reindex it. Now, I get the error message that the table is invalid and needs to be validated? Also, when I try to open it in the editor, the message that the .dbf file did not match the entries in the database. I've added fields to my tables before and have never had this problem. What did I do differently?

You did it while the table was disconnected from the .dbc - this may happen when you have a copy of the table in development, change the structure, and then copy the altered table into the production location, without copying the .dbc as well. The production .dbc will complain like this, because the information about your table is not what table actually has.

My usual cure for this is to do these changes programmatically, i.e. any changes I do to development tables are checked when the executable runs on the user's side, and if they're not done, the production tables are altered. This way each set of tables remains connected to its DBC, never leaving the directory where it resides. The target DBC will automatically register any changes to the table, be they done programmatically or interactively.