There have been some serious problems with the latest updates from VMware.
ESXi 5.5 Update 3 there was a problem with deletion of snapshots: KB2133118
ESXi 6.0 Update 1 and earlier has a problem with network disconnection: KB2124669
This problems are solved with this new releases.
ESXi 5.5 Update 3a (EP8) release notes can be found here: http://pubs.vmware.com/Release_Notes/en/vsphere/55/vsphere-esxi-55u3-release-notes.html
ESXi 5.5 Update 3a download: https://my.vmware.com/group/vmware/details?downloadGroup=ESXI55U3&productId=353&rPId=8948
ESXi 6.0 Update 1a (EP3) release notes can be found here: http://pubs.vmware.com/Release_Notes/en/vsphere/60/vsphere-esxi-60u1-release-notes.html
ESXi 6.0 Update 1a download: https://my.vmware.com/group/vmware/details?downloadGroup=ESXI600U1&productId=491&rPId=8761