"
The problem was that "Internet Explorer 8" was installed in the host machine. Uninstalling it solves the problem, and you get no more svchost.exe children for ThinApp applications.
You can replicate this problem installing IExplorer 8 in a clean VM with Windows XP and running some ThinApp packages such as Adobe Acrobat, firefox, etc.
"
Thanks for information. I will ask our QE team to look into it.