Same issue for us.  Workpapers CS.  1st export no issues.  Make a change in WPCS and export again and that's when ProSeries freezes up and corrupts the tax file.  No longer workable file even if you delete the TB .txt file.  Open the tax file and uncheck the automatic update box but the tax file will not save.  Pops up a 10250 error.  Basically killing that file and any work done in it.

Its a .txt file.  This really shouldn't be this big of an issue spanning over multiple Trial Balance programs.