I want to have clean ubuntu every time I turn on my netbook. How to do this ? I was using live iso (from usb) but it's very slow. I want to have no data on my computer every time when I turn it on, no browser cookies, no music, no downloads etc.
You can just use the Guest account of a freshly installed Ubuntu. It will be reset every time you logout.
As far as I know you can reset all settings of gnome and related things but if you are talking about package management and all then I think it is difficult!
The best way is to create two accounts One as Administrator and other as Student.
Don't add this student user into any sudoers file etc.i.e don't give root access to student account So that These users will not be able to install or remove anything related to system.
If you want to clear all the settings and remove all the data from this student at the time of booting then you can write down the shell script for this and then add this shell script in startup applications.So everytime you reboot your PC this shell script will run and it will do the task! Resetting wallpapers, clearing history and cleaning the user home directory can be easily done with a shell script.
hope this helps!