ESXi 5.5 Update 3 was released on September 16, 2015. Since it was released it has emerged that after upgrading an ESXi host to this update, a snapshot consolidation task can result in the relevant Virtual Machine suffering an outage.
This disruptive issue occurs due to a segmentation fault when changing the snapshot tree data-structure.
More details are here:
Clearly you should not install this update if your data protection software relies on VMware snapshots. If you have already installed it, consult the VMware link above for a work around strategy or suspend your snapshot scheduler (which you may need to do from your data protection software) while we wait for a fix from VMware.