I had the same problem with Sygate.
The workaround for Sygate,(as posted by a user on the Sygate forums), is to "allow" Generic Host Process for Win32 (svchost.exe),but also make sure you uncheck the "Act as server" option.

Right click the Sygate icon in the sys tray and select Applications.Look for Generic Host Process for Win32 and select "Allow".Then click the Advanced button and uncheck "Act as Server". Click OK,OK.

You should now be able to access Windows Update.