More info on the problem!
Forgott to tell you that for several times it worked fine to change port but for some reson I did not manage to close the sessions on teh web properly and my macbook pro went in to overdrive trying to run several sessions of the webpublished file. Så I went in and closed down all processes via Activity monitor. Everything worked after that for several weeks until I closed my laptop in the middle of some work in the database and the next time I opened the program - I couldn´t.
Thank you for posting.
It sounds as if the publishing is conflicting with other instances of itself. Does the problem stop if you close all FileMaker processes in Activity Monitor or reboot?
You could try to clear out the preference files by removing any com.filemaker files from /Users/<username>/Library/Preferences.
If putting the computer to sleep while the web publishing is running seems to be causing this issue, it may be best to close the databases or the FileMaker Pro application before doing so.