there's indeed a problem with April's Windows  Explorer  update  MS06-015 (908531), for people using either:

Hewlett-Packard's Share-to-Web software [ Namespace Daemon (Hpgs2wnd.exe) ] or

Sunbelt Kerio Personal Firewall

 

for details, and a "resolution", see here:   http://support.microsoft.com/kb/918165