I've tried to upgrade squeeze to wheezy following Falko Timme "How To Upgrade Squeeze To Wheezy" except that after updating and upgrading squeeze I logged out from the VT because I don't like vi editor. I logged in X and used gedit to update source.list for wheeze. I've done it as sugested in mentioned HowTo. I've logged out X than logged in VT and done apt-get update, apt-get upgrade and apt-get dist-upgrade. Before reboot I've reinstaled grub following advise in one of comments. After reboot system started but it was not wheezy, it was squeeze a bit higher version. I had 6.0.3 now I have 6.0.8. I didn't know what to do I decided to do apt-get dist-upgrade once more. Nothing changed. Still I have squeeze. Besides it is a big mess in my system. Checking in aptitude I see 701 packets holded. Aptitude says their update will cause dependency breaking for other packets. Can anybody explain what I did wrong and what can I do to clear this mess?
Most likely a wrong entry in sources.list or no dist-upgrade was run yet. Please post your sources.list file.
Problem resolved Thanks Till, I've managed to resolve the problem. I read upgrade guide once more. It reminded me thad I had the "Could not perform immediate configuration" error. I've made apt-get dist-upgrade -o APT::Immediate-Configure=0 and I succeeded.