For simplicity's sake, put one of the azw files in the same folder as mobi2mobi.exe (not the gui program, the folder where all the mobiperl executables are). Then open a command prompt and change (cd) to that folder.
Typing:
Code:
mobi2mobi bookname.azw
...and hitting Enter will spit out everything that is known about the file. At the top of that list will be "Database name:" The title of the book (or part of the title) should appear there. If there is nothing there, then the file won't work with Mobi2Mobi-Gui. In that case:
Typing:
Code:
mobi2mobi --databasename "Some_Name 32_characters or less" --outfile "New ebook file name so I don't screw up the original one.azw" "bookname.azw"
...and hitting Enter will create a new azw file (with the name you gave for the --outfile parameter) that should work with Mobi2Mobi-Gui.