If you happen to be using a thumbdrive to store these documents, you might try Disk Utility's "First Aid" function on it. Several apps exhibited baffling file-saving behavior with my thumbdrive, including being able to create a file but not save it after that; but instead you could "Save as" and write over it in the same location. The problem hasn't returned after "repairing" the drive, it it doesn't explain all of TurboTax's failings... but give it a try if this is your situation.
