Comment 18 for bug 505085

For anyone struggling with this problem and searching for workarounds, the upstream discussion is a good read. Apparently, it is possible to entirely disable the housekeeping mechanism that is responsible for this problem:
https://bugzilla.gnome.org/show_bug.cgi?id=625609#c6

Doing so will
(1) disable purging of old thumbnails, so one either has to live with the thumbnail cache growing boundlessly, or implement a different workaround, such as the one suggested by Eric Link
https://bugs.launchpad.net/ubuntu/+source/gnome-settings-daemon/+bug/505085/comments/13
(2) disable the low disk space check and warning - if your disk is nearly full, you'll have to keep an eye on it yourself
(3) possibly disable other housekeeping functionality - when experiencing additional side effects, it might be a good idea to feed them back to the community

Of course, this is still a (somewhat unsatisfactory) workaround, and we're eagerly awaiting an actual fix from the upstream gnome-settings-daemon maintenance team.