Your observation that a blank file saves correctly is the definitive clue that the hardware is not to blame. The issue is almost certainly software-related. That is, either your environment (antivirus?) or data (one or more fields within your tax return contain a value, character, or format that triggers a bug in TurboTax's save routine?)
Your plan to test sections of their return is the right approach. The next time you have a working, uncorrupted file, follow these steps in order:
Save to a Local, Non-Synced Folder: Explicitly use "Save As" to save a copy of the working file to a location that is not synced with any cloud service, such as `C:\Temp\TurboTax_Test\`. This isolates the file from any potential sync conflicts.
Disable Antivirus Temporarily: Before saving, temporarily disable all real-time antivirus and anti-malware protection. This will determine if security software is interfering.
Run as Administrator: Right-click the TurboTax icon and select "Run as administrator." This ensures the program has all the necessary permissions to write to the disk.
Methodically Test the Return: If the file still corrupts after the above steps, the issue is within the data itself. Use the "blank file" that worked and, one by one, begin entering data, saving, and re-opening after each major section (e.g., "Personal Info," then "W-2 Income," then "Deductions," etc.) until the file corrupts. This will pinpoint the exact form or data entry causing the problem.
Good luck!
