Maybe I am missing something but here is the error I am getting:
Warning: fopen(isconf): failed to open stream: Permission denied
I don't see this file anywhere, I did have to however create a tmp file to get this far.
The isconf file is created when the install script has finished.
If you receive this error, it means the the mythreads directory is not writable by the web server. You should fix this problem and run install.php3 again.