When using the VMware Infrastructure Client GUI to connect to the VMware ESX Hypervisor, I encountered a nasty problem. It was not possible to upload a Virtual Machine image, or even an iso image to boot on. Every attempt to add a file to a datastore ended with an "IO error"popup, and the file was not copied.
The GUI was running inside a Windows XP virtual machine, running inside VirtualBox.
When running the GUI from a native Windows machine, it worked.
There seems to be an issue in the way the VMware Infrastructure Client GUI interfaces the VirtualBox disk driver.
VMware Infrastructure Client 2.5.0.
VMware ESX Server 3i 3.5.0.