2012年4月12日付けでBuild Number: 653509が公開されていました。
今回はvShield Endpointに関するバグフィックスのようで、XP/2003で通常より多くのメモリを使用することがある、また、システムやサービスが応答しなくなる、という事象に対するモノのようです。
引用元：VMware KB: VMware ESXi 5.0 Patch ESXi500-201204401-BG: Updates tools-light
This patch updates the vShield Endpoint Thin Agent drivers to resolve the following issues:
After installation of Thin Agent drivers in vShield Endpoint 5.0 on Windows XP/2003 guests, overall memory usage of the guest virtual machine might increase substantially with all processes consuming higher amounts of memory than usual. This behavior is not observed in Windows Vista and later. It results from a combination of the way the Thin Agent reads a file during its scan and Windows internal behavior.
The vShield Endpoint Thin Agent 5.0 might cause a service or the operating system to become unresponsive. This happens because the Thin Agent fails to correctly detect remote named pipe or mailslot connections opened by a software running in a guest virtual machine and instead treats these connections as files.
