Well the error you have there is from a line break that shouldn't be there (probably from your copy & paste). The first line should simply be a comment:
PHP Code:
// has to be in $this-> format in order for admin panel to write correctly
$this->absolute_path = "";
if ($this->absolute_path == "")
$this->absolute_path = dirname(__FILE__) . "/";
You should try to use the updated version however as it does contain several bug fixes / feature improvements. I would recommend deleting the script and re-installing. You could easily have a corrupted file somewhere or similar. This is the first thing I would try when troubleshooting. The next thing I would try would be manually editing the config file and setting the admin username to "user" and password to "pass" and seeing if those credentials work.
Sometimes the configuration file can become corrupted and it is for this reason that I recommend uploading a fresh config file (not simply attempting to confirm the user/pass that is within the file).
You may also want to try using a different browser. I have had people submit requests for support with similar problems that had their browser automatically changing their login values due to auto-fill features.