need help with ubuntu

I am new to Linux and I have been trying to get to Ubuntu to work. I got it to install once and work but I didn't know that the root account can be used with sudo, so I reinstalled it and had a screen resolution problem. So I reinstall it, and somehow it freezes up on me(I can't do anything - use keyboard or mouse) so I hold the button to shut it down. When i reboot it I found out my internet connection no longer works, so I reinstall it(see a trend here? :roll: ) and now when I try and boot it up I either get

<0> Kernel Panic - not syncing : Fatal exception in interrupt

or

<0> Kernel Panic - not syncing : Attempted to kill the idle task

or (if I run it in recovery mode)

I will get Starting Hotplug Subsystem and it will never say [Ok] to the right of it like the other commands above it does(sometimes this happens when I boot it up normally). It will just sit there until I restart my comp. Any help would be appreciated.

You did format the drive during installation right, not just installing upon the old install?

No, how do I do that cause I did reinstall it twice without formatting and it worked fine :?