I currently have Vista 64 bit and ubuntu 32 bit on two seperate disc partitions.I am trying to do a fresh install of Ubuntu 12.04 64 bit as i had mistakenly installed the 32 bit 12.04 a little while ago( I am clear that i dont want the existing 32 bit ubuntu or any of its files on my system). Now i have downloaded the ubuntu-12.04.4-desktop-amd64.iso and made a bootable flash disc with Universal-USB-Installer-126.96.36.199 utility.(Exactly the same procedure as i had followed for installing the 32 bit system but the iso now i used was the 64 bit one. The problem at hand is that when i boot my system with usb disk as the first option then too my pc does not boot from the usb and what i get is the ubuntu screen giving me an option to either load ubuntu or vista. What should i do?
Check whether the ISO file is not corrupted.(you may like to redownload the iso from "http://www.ubuntu.com/download/desktop/questions?distro=desktop&bits=64&release=lts" Try using a different USB drive or remove and insert the flash drive a couple of times after booting up in Vista, then eject and safely remove the flash drive, (Do not physically remove the flash drive from the system at least i did that with mine). Restart the PC and the system will get booted from the flash drive. You will I get the following three options for install after the message "your system has vista and ubuntu 12.04 already installed on separate drives" . please choose any one option below 1.erase ubuntu 12.04 and reinstall. 2.replace vista with ubuntu. Choose "Something Else" during installation. Select the partition that has the mount point "/" and format "ext4" as the place to install (this is the initial place where earlier version of ubuntu was installed). Make sure the Format Partition check box is marked, so that the earlier data is wiped out. Do not make any changes to the swap partition and where to install the bootloader. let them be the default values. You shall be done.