Hello everybody,'
I have a very similar problem. Whenever I try to save my session with the menu option TTAX just closes and next time I open it most of the entries are lost. It is always the same, re-boot or re-install did not fix the issues either.
Here is the workaround I found:
Close TTAX using the X on the upper right corner of the window. Before it actually closes TTAX will ask if I want to save my session and surprisingly it does save everything I entered and all works when I open the file next time.
Good luck! Robert
