Checking my error logs (admittedly for the first time on a 5yr old site) it is virtually full of items like this:
File does not exist: /home/****/public_html/directory name/null, referer: [mysite.com
...] directory name/filename
[Mon Jun 03 22:21:13 2013] [error].
A link goes from the name referer to the index page in that directory. Using a link checker show no problems.
What does this mean - where does that null come from