I received a MS Word file with track changes from my boss. It is in 2007 version and my version is 2010.
Strangely (unsurprisingly) my version can not save this file. MS Word is still so dodgy.
A trick to solve this problem:
1. open the file;
2. save as 97 version, .doc file. the equations are all converted into images. looks ugly.
3. save the 97 file as a docx file. the images come back as equations. and it can be saved!
Live in Rubbish, get used to Rubbish:)