I managed to boot Ubuntu from sd card with the new Uboot-bootmenu bootloader, but now I have a different problem. When I issue the apt-get update or apt-get upgrade some error occures:
First it show that Connecting to ports.ubuntu.com
Than it cannot download anything and gives me this error:
E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing?
After this I issued the recommended command it gives this error:
Err http://ports.ubuntu.com precise Release.gpg
and some other similar lines then:
W: Some index files failed to download. They have been ignore, or old ones used instead.

Please help me because I was also unable to install Lxde and the unity is stil full with bugs.