oddly, as I was poking around the other threads, I came across another recent thread that seems to indicate that the issue may be Tomcat related : http://www.liferay.com/community/forums/-/message_boards/message/251533 . (It is a bit further down in the thread). You may want to try starting out a fresh instance from one of the Liferay / Tomcat bundles, or take a look at http://www.liferay.com/documentation/liferay-portal/6.1/user-guide/-/ai/lp-6-1-ugen11-installing-liferay-on-tomcat-7-0 to install liferay on an existing Tomcat application server.
***actually, taking a look at that old thread once again, I get the feeling that the directory stucture looks incorrect. Not sure if you having the same directory structure at the other thread, but the entire Liferay .war should be extracted within the ROOT folder In the old thread below, it looks like they extracted everything into "webapps" when it should be all under "ROOT".
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