T_SL is generally caused by multiple files of the same name via version control. Usually the result of CVS or SVN updates adding multiple versions of the same file to avoid overwriting changes that were made in an environment.

Check the directory of the file that is causing the error, and there is likely several versions of the same file in the directory.

For example:

filename.mine
filename.r98
filename.php

PHP has a hard time processing this because sometimes the *.php file has merged changes that are faulty comments and such.

Remove all the files, run a SVN or CVS update, and make sure only one copy/version of the file is live, and voila!