A semi disastrous day. I thought that I'd really messed up my laptop. I had downloaded a film in MP4 format, but I hadn't loaded a suitable player, so I thought I'd switch to the evil Windows. It wouldn't play the file,and then it started giving messages about updates. I wasn't having any of that, so I tried to switch back to Ubuntu. No luck - it kept booting up windows, go it had obviously corrupted the boot file. I had to go into the setup and restore the boot menu. Seems OK now, but I won't go near windows again and I've loaded VLC player.
When I get a new laptop, I was thinking about wiping Windows completely, but I was wondering if that might affect the warranty.