G-Star,
I don't know about celtx, but if you give me more information, I can try to help you out.
Can you make a .pdf file from that software? Certain platforms allow .pdf creation as a default printer output. This option will (should?) retain your formatting and protect your data by making it a little more difficult to edit.
If you are serious about your work and have a credit card and a couple of bucks, you might want to register the script with the writer's guild <
http://www.wga.org/>. Follow the links from the main page.
If you are using MS Word is your main piece of software, I can try to get some Word templates to you that might make it easier. You may lose your formatting, but once in Word you'd be able to reformat quickly with style-sheets.
Hope this is helpful...