Since updating to 15.10 on my Thinkpad T420, I've experienced random freezes periodically. Usually within an hour of using the laptop. It ran just fine on 15.04. I've tried looking at /var/log/syslog but I'm not quite sure what I'm looking for. There's obviously lots of errors and warnings that seem less significant.
When it freezes, I can't switch to tty1, can't do REISUB, and usually the cursor doesn't move (although 10 minutes ago, while in Chrome, the page I had open stopped responding, I refreshed, and while it was refreshing the page, icons and such in and outside of Chrome gradually stopped responding one at a time). Not unlike when I've had a HDD failure in the past. I have a Samsung 830 SSD on that note.
Suggestions?