I have a modification to the .htaccess file (from do_not_upload folder), and am using mod rewrite friendly URLs.
example:
http://www.mydomain.com/threads/425-...=2510#post2510
The site is also installed in the root, not in a sub folder. ex:
www.mydomain.com not
www.mydomain.com/forum/
www.mydomain.com/images/osbrowsericons/ is the true path (vs
www.mydomain.com/threads/images/osbrowsericons/ virtual path)
I bet it has something to do with finding the full path, or assuming it to be the same as the rewritten url.
If you want to take a look, i'm fine with that, but I just wanted to run the above by you first; as a possibility.
General comment: The UNKNOWN LOCATION errors in the whos online problem I was having previously were due to it looking in the virtual path, rather than the actual. I fixed that one by changing the FAVICON variable to have the full path instead of just the filename. I guess it reads the "base path" as the virtual.