Hi Nicole,
where did you see that you need this specific ccs version? Our usual recommendation is in fact normally the latest version, v5.5. In addition to that ....v4.2.5 for some reason I would need to discuss with you offline.
My ID is a link you can use for a friend/conversation request. In the mean time I would recommend v5.5.
http://processors.wiki.ti.com/index.php/Download_CCS
Best Regards,
Lisa