Because of a flash error caused by a .swz signature expiring on May 5th an issue has appeared for vSphere Web Client in vSphere 5.0 environment (depending on the version of flash player).
Temporary solution is to replace 7 .swz files (after downloaded delete version number in file name):
into each of these locations on vSphere Web Client server (while the vSphere Web Client service is running):
D:Program FilesVMwareInfrastructurevSphereWebClientDMServerworkosgiconfigurationorg.eclipse.osgibundles38datastoreorg.eclipse.osgibundles1121bundlefilerslbD:Program FilesVMwareInfrastructurevSphereWebClientDMServerworkosgiconfigurationorg.eclipse.osgibundles38datastoreorg.eclipse.osgibundles1281bundlefilersl
and clear cache on web browser.
If the vSphere Web client service is restarted these steps needs to be performed again.
There is no permanent fix yet. link_to_vmware_kb