For those who use VMWare extensively in their organization, beware that the latest round of Microsoft updates may break your older vSphere 4 client under all versions of Windows. More information from VMWare on the problem can be found here. Users of vSphere 4 Update 1 should not be affected.
The primary update in question is KB Article 980773 – a .NET update. Removing it will solve the issue for most users. Some users have found that uninstalling all .NET updates pushed out as part of the June 2010 Microsoft update cycle is required. Other may need to upgrade to the latest version of vSphere may solve the issue.
Anyone who manages VMWare servers from Windows is affected. I wouldn’t recommend that users not using the VMWare vSphere 4 client uninstall these updates before first understanding the risks of doing so.