I had Ubuntu 12.04 on my laptop but it went unstable after some automatic updates. The Ethernet connection would not work anymore (it couldn't find any network devices anymore) and the only way to turn the computer off was by removing the battery. I also had many pop-ups with error messages.
I've tried many things now - installing 12.04.0, installing 12.04.3 and 13.10, but it's always the same (errors and the number of error messages vary a bit - for example with one installation the touchpad didn't work either). It doesn't matter if I do the "Erase and reinstall" or "Something else" and choose manually to format Ext4, the problems are still the same. But, when I run Ubuntu from my USB stick, then everything works! So, the clean install is not really clean? How can I get it to really delete everything and get Ubuntu to run from my hard drive as good as it runs from USB stick?