Thanks for the reply, I fixed the freezes months ago though. 
I replaced Win7 on this machine. It was actually the nasty Bug #109051, which causes total freezes on computers using low end Bay Trail CPUs. I edited my grub config file as described here. One of the reasons I love the UM community is that the solution to this issue was written down on a common problems and workarounds page!
No more freezes, the only downside is that the computer uses somewhat more power since I disabled CPU power saving modes.