Hi, ...
Try StartupControlPanel =
http://www.mlin.netStartupControlPanel, will manage all "Startup Programs", from an old Windows 95 and up, it even work in my Vista 64 bit Ultimate. To use it = to not start a software, deactivate checkbox in the same line, and also try to move some start section like startup user section to a local startup machine section, to see if you have multiple start of a software, ...
At my side, ... I will try with VMWare, Windows 98 SE French, with the last Avast Version 4.7.1074 Home, ... and Professional evaluation, ....
By the way, ... have you the Avast Home version or the Avast Professional version, ... ?
Sylvain