upgrade or install?

[pierreu1]

I ran into some problems with my fan no longer working, possibly damaging Ubuntu to the point where I am asked to remove some old and unwanted kernel images before I can proceed, but I have not been able to do it using janitor, synaptic, and the terminal!

So, I want to make a clean upgrade or a clean install. It probably won't fix the fan issue, but I do not have the original windows XP recovery disk to dual boot, so...

I thought I did a clean upgrade when I moved from Oneiric to Pangolin last week, but obviously it was not a clean upgrade! What should I do to make it so? How should I respond to the messages that will make it so when I upgrade? Or should I just install Pangolin?