Evilrix is correct - you need admin rights to install WinPCap, mainly because you are installing a device driver onto the machine, and access to the directory into which device drivers are needed usually is limited. Update June 5, 2015: WinPcap 4.1.3 works on build 10130. Update May 13, 2015: WinPcap 4.1.3 began to work again in Windows 10 preview 10061 and continues to operate in 10074. Hopefully, this trend continues - but I wouldn't count on it. But we still need to encourage Riverbed to update WinPcap from NDIS5 to NDIS6.
I recently installed Wireshark on a Win 7 host, but now it won't let me start the NPF service. I get: C:Windowssystem32net start npfSystem error 5 has occurred.Access is denied.That's strange, because I am in the local admins group, and the SDDL string for the 'npf' service shows that the RP and WP permissions are allowed to the built-in administrator group.