Changing backgrounds multiple times causes a system freeze.

[horsemanoffaith]

I recently updated ubuntu-themes to the Zesty repo. The themes work correctly, but if you change backgrounds over and over (selecting 20-30 different backgrounds), the system freezes. You can't do anything except for switching to a tty and restarting lightdm. This also applies to the current version of ubuntu-themes. I have unity-control-center updated to the most recent version (15.04.0.17.04.20161125.1). Any ideas on what may cause this?