I have a Dell Studio-1558 which I've been trying to dual boot. I messed up with the creation of partitions and have lost the ability to boot into Windows 7. Now I'm trying to install Ubuntu 12.10 on it through a bootable usb device. I've created an ext4 partition of around 10GB and commenced the installation process. However, it's been stuck at the last step: 'saving installed packages' since the last two hours. Also, when I click on details, it tells me that 'no server suitable for synchronization found'. Now I don't know whether I should cancel the installation midway as it has already messed up my system once.
Press Alt+F2 to bring up the "Run box", and type in "xkill". Hit Enter. Your cursor will now be an x. Anything you click would die. Click on the installer. Restart. Remove the boot device, see if Ubuntu runs off the hard-disk, if it doesn't you will have to re-install. Also check whether you have sufficient space where you're installing Ubuntu.
And the ability to boot into Windows 7 can be simply restored if you have a Windows 7 bootable DVD, just boot into and repair the startup.
Hope this helps.
A clean, fresh install with a CD is the best way. Also, search for your laptop model on this site and see if this problem turns up elsewhere on askubuntu...
Try CD instead of pendrive...