ip address redirects to ibooktemp.local - huh?


Hello. I have started the Apache web server on my iBook. I'm running OSX 10.4.2. When someone outside my network enters my external IP address, such as http://xx.xx.xx.xxx:80/ , they can see the default file I placed in Library/WebServer/Documents just fine. However, when they enter http://xx.xx.xx.xxx:80/~myshortusername, their browser tries to redirect to http://ibooktemp.local/~myshortusername/ . Of course, nothing loads for them, but on my computer I see the OSX web default page.

I set up post mapping the the Airport Admin utility so that Public Port and Private port are 80, and so Private IP Address matches the local IP address shown in the Sharing panel, which is .

Does anyone know what this might be a symptom of? Why does http://xx.xx.xx.xxx:80/~myshortusername try to redirect to http://ibooktemp.local/~myshortusername/ ?

And, what is the difference between putting your files in Library/WebServer/Documents vs. putitng them in /Users/myshortusername/Sites?

Thanks very much.