Sygate may have been set to block avast at some stage (it would have asked you to allow it)
1.right click on sygate tray icon
2.select applications
3.remove any avast4 applications (better than changing to allow incase some avast items dont need access)
(the next time any avast app. trys to connect, sygate should ask you to
allow it, click yes and tick remember box). these will be added to the applications list (they cant be added manually, only when asked)
based on SPF free version.
I presume you have correct settings in avast connection ie by dialup?
Also like tech says, having more than 1 firewall/av running can cause problems and possibly even installed, if registry settings/dlls clash.