The App-V Client (running under Windows XP) may fail to stream from App-V Server (or IIS Server) when running IPV6. You may get an error similar to the following:

[08/18/2011 10:23:32:058 JGSW ERR] {tid=10CC:usr=steveth}
The Application Virtualization Client could not connect to stream URL 'http://server/content/application/package.sft' (rc 16D1100A-0000E005, original rc 16D1100A-0000E005).

[08/18/2011 10:23:32:058 PMGR ERR] {tid=10CC}
Failed to background load package {package} (rc 16D1100A-0000E005).


[08/18/2011 10:23:32:059 AMGR WRN] {tid=10CC}
Attempting Transport Connection
URL: http://server/content/application/package.sft
Error: 24604F0A-40002EE2

Windows XP supports DNS queries only over the IPv4 protocol, but will support IPv6 queries (such as PTR and AAAA) which is why name resolution will fail.  Unless the the WinXP client is dual-stacked with both IPv4 and IPV6, you may have issues with the App-V client and IPv6.

It is important to note that this problem is only found on clients running exclusively IPv6 on Windows XP clients only.