Whenever I 'Save' a Word document, I get the Save As dialogue instead of the file just being overwritten.

Word (OS X / 2011) has the correct filename of my document in the Save As field but it doesn't do the saving unless I then click the Save button.

None of my files are 'locked' and I don't have autosave on. I've tried creating new documents, resaving old ones with different names ... it makes no difference.

Any suggestions as to the cause?

Thanks everyone.