Hey there !
I bought a laptop two months ago and had Windows 8 replaced by Ubuntu last month. My cousin did it. He's a kind of program tester or something, so he knows his stuff.
He had problems installing Ubuntu because he wanted me to keep Windows (he said some programs don't run on linux, like his taxes one, and it's better if I keep windows just in case). He had Ubuntu installed but at the start, when he chose windows, it wouldn't open. He figured out after a while that I needed the Windows installation cd (which I don't have). So we just left it like that, waiting for me to put my hands on a cd to be able to use windows if I wanted to.
Two weeks later, I started having problems, computer locked, touch pad not responding... and I sent reports the way they said (I figured since it's linux and not windows, it might help !). But it got worse, and for the third time now, Ubuntu was totally blocked and the computer started with windows instead, which it was not supposed to be able to. All my data are on linux ( not much, I made copies for almost everything, but things my favorite sites and such..., and a part of Calibre that I didn't finish saving, but never mind).
Any (easy) way to do something about it ? Because my cousin lives quite far, so I'll be on my own on this one.... I lost internet last night, and only got it back this afternoon, don't know what's gonna happen next...