Magento Downloader hangs when trying to install Mage_all_Latest

I have installed magento version 1.9.1.0 from a few months now everything works fine. Since several weeks I have been trying to update Magento via Mage_All_Latest package via Magento Downloader, but nothing happens. I've tried this in the last weeks with version 1.9.1.1 - and as of today with the brand new 1.9.2.0 - it doesn't matter which one - it doesn't work. In a green status window, it tells me "Checking package dependencies" - and what it is. No error, no message - just nothing. I've tried this several times, nothing happens - for hours! The package is not in the /downloader/.cache-Directory directory. When trying to update individual packages manually via the bootloader, it always tells me things like

CONNECT ERROR: Package community/Cm_RedisSession 1.9.2.0 conflicts with: community/Mage_All_Latest 1.9.1.0" - but i cannot update this package...!

      

        
        
        
      

    

There is enough free space on the server. The bootloader itself has no problem - I tried to install all the available packages in various respects and some worked:

Checking dependencies of packages
Starting to download Lib_Varien-1.9.2.0.tgz ...
...done: 157,974 bytes
Installing package community/Lib_Varien 1.9.2.0
Package community/Lib_Varien 1.9.2.0 installed successfully

      

        
        
        
      

    

I cannot access the server via SSH. Is there any other option to update this package? do I have to download a complete new Magento installer and override all files manually? or can I upload this "Mage_all_latest" -package to magentocommerce website and replace all files manually? Is there any other option? Does anyone have an idea what to do? No error message :-( Thanks.