This is the announcement of the forced update to 4.7.892
http://forum.avast.com/index.php?topic=25348.msg207272#msg207272

What this means is that if you still don't have 4.7.892 installed, it will come to you (silently) with the next VPS update and you'll be asked to restart your computer. The reason is that the new VPS files need the latest version.

Can the vps file start from 4.7.892 up to now?