Hello, I work at a small IT firm and have encountered a problem with a client where any document that they try to save in Word 2010 will try to be saved in Word 97-2003 format. I've gone to Options>Save>Save files in this format and confirmed that it is set in Word Document (.docx) format. Furthermore, each time I tried to save I made sure that "Save as Type:" is set to Word Document. Attached is the message that occurs when you try to save any document. This is happening even if you open up a blank document and it is happening on multiple computers. Any suggestions?

Check the File Block settings.

File > Options > Trust Center > Trust Center Settings > File Block Settings.

Is the Save box at the top for Word 2007 and later file types checked? I suspect that is what the error message you showed means.