I have installed Ubuntu 13.04 some days ago. Now I am trying to update software using Update Manager, Software Sources, but it is showing that it is downloading from archive.ubuntu.com (blah, blah, blah) but actually it isn't doing anyting. I thought this is my network connection problem, but it isn't cause i can browse to any site or download anything but i just can't update my software. I also have tried the command line way, but it always gets to 27% and just stops there. Now i'm stuck. What to do, anyone pleas help me?