We found a bug in MS Word 2013 when opening a WordProcessingML file with nested tables. Some parts of the tables in the editing mode are not visible and only will show up by changing the font, font size or resize the tables. The read only mode is not affected by this problem. The same file can be opened with Word 2003 and Word 2010 without any trouble.
This bug is critical for our customers and we need this to get fixed asap.
I can provide a sample WordProcessing file, if needed.
Thanks.