ModX Evo: Unable to login to manager (returns to the login page)

Hi everybody

I recently updated my old version of Evo to the latest one (1.1) by using the Update Exiting install option.
I did that because the host updated to a newer version of PHP
Everything was fine until some days ago (no other change was made since then accordig to the host)
Suddenly when I try to log in to the manager, I enter username / password and when I click the login button it returns to the login screen
I couldn't find what was wrong so I decided to make another "Update Existing Install"
Everything looked fine to the Pre-Install validation (screenshot 1) but when I try to install it i get the error "Connection to database failed" (screenshot 2)
I tried to change the "session.save_path" parameter of the php.ini to an existing writable directory but it did not help
Any ideas?

Thanks in advance
Dimitris