The open-vm-tools extensions have been updated to version 11.2.0. This fixes a memory leak which crashed some of my VM's. VMware was nice enough to fix it when I pointed it out to them. The details are at
https://github.com/vmware/open-vm-tools/issues/452 and affects both 32 and 64-bit. This should be considered a must-update, or at the very least a really-really-should-update.