I deleted my main user account, how can I set ubuntu to not automatically log into with that old user account?

Ok, so I hadnt used Ubuntu since Lucid Lynx, because it had become slow. Now I went in, updated to Narwhal and I saw that some programs were still slow, so I created a new User account , I set that new account to be an admin and deleted the old admin User account, thinking nothing would go wrong because I'm used to doing this in Windows.

Now whenever I boot it automatically logs in to the OLD user account without giving me the option to log into the new user account and gives me the following string of errors (I replace the name of the user account with olduser for convenience)

cant update ICE authority/home/olduser/.ICEauthority problem with configuration server

(/usr/lib/libgconf2-4/gconf-sanity-check-2 exited with status 256)

Nautilus could not create the following required folders:/home/olduser/desktop,/home/olduser/.nautilus,

Afterwards Ubuntu shows me the default desktop image and nothing else. The only way to get out of this for me has been to wait for the screensaver to appear, and use the unlock dialoge to switch to my new user account. That is how I booted and how I'm writing now but clearly I'd like to boot more normally, how can I set ubuntu to log into my new user account instead of the old user account?