I've just added some Windows 7 virtual machines to an existing VMWare vSphere 5.1 cluster. The hosts and vCenter are 5.1 with current updates via Update Manager.
Looking at the vSphere client performance graphs, I see random sustained jumps in the guest CPU utilization. These are new VM's with no software installed. They were trimmed-down and optimized according to this guide. The VMWare guest tools are installed.
The systems are idle as this is happening. There's no corresponding activity within the guest's Task Manager or Performance chart.
Any thoughts on what the issue could be? I suspect a guest tools/version interaction, but a root cause would be helpful.