The Immunet 3 Installer (version 18.104.22.16871) does not work under Windows XP service pack 3. It fails with this error: Output folder: C:\DOCUME~1\Owner\LOCALS~1\Temp Extract: C:\DOCUME~1\Owner\LOCALS~1\Temp\iprdF2831AAE-7FF7-4A79-9135-1C36AC71A506.dll Found policy - C:\DOCUME~1\Owner\LOCALS~1\Temp\policy8095A2F4-8928-4472-8CCC-D4FDB516BDD6.xml Detected Win32 Platform Downloading Installer ... Download failed. Please check network connectivity and retry. Completed I have received the same error for both a Dell laptop and a generic brand desktop, both running XP SP3. Installing the old offline installer, protect-en-us-22.214.171.12470-32-tcp-policy, works fine, and can be then upgraded to 3.1.13, using the inline upgrade tool.