Question : Sending and Receiving Multicast From Cisco VPN Client

I currently have setup a remote access VPN client with split tunneling enabled to an ASA 5505. The tunnel works and all clients are able to connect successfully and exchange unicast packets; they however cannot exchange multicast packets. Is there a way to make this possible? When I define my interesting traffic, can I specify it as GRE instead of IP in my ACL?

Answer : Sending and Receiving Multicast From Cisco VPN Client

I found a thread for microsoft Windows XP on the support.microsoft.com that seems to be your probleme:
title:"The Windows Installer Service Could Not Be Accessed" error message when you install a program in Windows XP

http://support.microsoft.com/kb/315353/en-us