Error in the RPC receive loop: RpcIn: Unable to send

Problem:

Error message above is flooded in Event Viewer on a MS Windows VM guest when vmtools upgrade is performed to 5.1 but I encountered the same error recently after fresh installation of VMWare tools on new VM guest.
Error message for Linux guest is the same. According to KB2036350 - this should be fix the problem, however the tools.conf sometimes is not created.

The Performance Overview tab fails to display into vSphere Client and VCSA 5.1

Problem:
I cannot view the Performance Overview tab when connecting to vCenter Server Appliance using the vSphere Client 5.1 on MS Windows XP / 2003.

Variations of the error message in the Performance Overview tab:
- This program cannot display the webpage - more often seen
- Navigation to the webpage was cancelled - rarely viewed

Jumbo frames in virtual FreeNAS 8.3.1 on ESXi 5.X

... and how to setup vmxnet3 vNIC and Jumbo frames

Problem:

When I set jumbo frames (MTU=9000) on em0 vNIC in virtual FreeNAS I can't get frames bigger than 1500 between the peers, even configuring mtu=9000 in all network elements between end points. Do not be fooled if you see this:

[root@freenas] ~# ifconfig em0 mtu 9000
[root@freenas] ~# ifconfig em0 em0: flags=8843 metric 0 mtu 9000 options=9b
ether 00:50:56:87:xx:xx options=9b ether 00:50:56:87:xx:xx
.....

I did some unsuccessful tests with em0 (in my case vnic is recognized as intel 82545EM) and MTU=9K. Eventually I could not get real jumbo frames between FreeNAS and other vm even inside vSphere host. Probably exception is being in the E1000 driver used by FreeNAS virtual machine though this also depends of physical NICs. em(4) supports variations of the hardware - some do jumbo frames, some don't. It could easily get a lot quirks in a VM, depending on how the VM emulates the card and the mode of networking used. This should show which of the Intel cards is being emulated.

# pciconf -lv | grep -A3 em0

VMware VM - changing the MAC address

The conversion of physical to virtual machine is related to change of the MAC address of the network interface. In some cases this can be a problem when software is installed where the licensing is bound up to the MAC address. To avoid the automatic change of MAC address, you should not move the machine (configuration file of VM) to another host or different datastores on the same host.
If the VM is a member in a DRS cluster and automatically or manually movement between different hosts is needed, then we must set up MAC to static and we can achieve this in few ways.

Method #1. vSphere Client

If your attempt failed with the error below - go to method 3
“The MAC address entered is not in the valid range. Valid values are between xx:xx:xx:xx:xx”

Method #2. MAC address change from within the network adapter settings in Windows.
First of all ensure that vSwitch (virtual port group) security settings MAC Address Changes and Forged Transmits are set to