Although I've used this distro family since 2000 pre-fork Mandrrake7.2 I don't consider myself a Guru by any means, I would like to share what happened when I upgraded it may be of help

Firstly I couldn't get the on-line upgrade to work for me, but thinking now that's probably due to my slow broadband. First of all I downloaded the 64-bit disk installed it keeping the partitions and then using the /home as my system backup thinking about it I probably cause problems doing that by re-using my set-up files and not allowing the installation software to choose the best window manager for my hardware. II did complane of my disto being slow that's cured now by the auto update in command line and a change of display manager.