After lots of trial and error, and copying and pasting, I have finally gotten the tab order to work the way it is supposed to. I moved the project to my older PC which has Office 2003 (although I don't think the version had any impact on the resolution of the issue). I was finally able to get the text fields working by cutting one frame, setting the cursor in the frame of the next field, then pasting. The checkboxes didn't seem to work with the rest of the fields, so I had to go back and reset them similarly afterwards, and some combination of having the correct frame selected when pasting seems to have finally paid off. This is totally ludicrous that I had to go to these measures to set a simple tab order. I only hope that the order stays put as I make the rest of the changes that are coming my way fom the client.