:S Imposible to install Piwik in any of his 3 last versions!

I’ve just downloaded and installed the three last tagged versions (included latest) and all of them throw php erros even before installing the application!!! I think is a bad start for a suppoused proffesional tool like this. Sorry for the anoyning topic but im very frustrated and didnt find any help at all in forum neither documentation.

For demostration porpouses, all of these people had the same critical problems as me for sure, and more over I think is a security issue:

with latestand 1.9.x version:
https://www.google.es/search?q=Fatal%20error:%20Class%20’Piwik_Controller_Admin’

with 1.8.x version:
https://www.google.es/search?q=%22PHP%20Fatal%20error:%20Class%20’Zend_Session_Namespace’%22

whats the problem??
thanks in advance

Any ideas?

REupload all files properly and it should work. If not post a screenshot of the erro you get