Hi Dustin,
Wait a sec. The original error message suggests a problem with the data connection, not with the XSN. Please right click the XSN. Choose design. Go to Tool->Data Connection and try adding the connection again. If you can't (because it's a submit/receive associated with your main data source), then you will have to crack the XSN. Rename it to .CAB and copy the files out of it. You'll want to look at the manifest.xsf. It's going to require a lot of time if you haven't done this before. You could easily purchase a block of consulting time from us, send us the XSN and some info on your DB and have an answer in short order. One other thing to consider is whether or not the DB changed. If you changed a datatype in the DB and you remember which one you changed. Then, try changing that back. Also, if you added a column to yoru table, that would probably cause a problem. These problems are common issues with the direct connection from InfoPath to SQL. To help people out, we have developed the Qdabra Database Suite which removes the need to create a direct connection. These kinds of changes won't make your form stop working. Anyway, let us know id we can help!
Patrick Halstead
Project Manager at Qdabra