Sounds like a possible corrupted database file. A clue sometimes that this has happened is if your documentation files are huge. Those files have a file extension of ESD, LCD, LDA, SCD.
DirectSOFT6 makes a backup copy of your project every time you save it. So, it is possible that you have a backup copy of your project that is not corrupted. This AutoSave feature stores files in:
c:\Users\Public\Documents\DirectSOFT6\Projects\Backup\AutoSave\<YourProjectName>\<date_time_stamp>
By default, it stores 3 or 4 previous copies. I forget which.
Browse to that location and see if you can open one of those saved files. Let us know if this doesn't work.