After some “further investigation” it seems that the latest Avast update (for me) being right before the problems started were merely a coincidence, however, uninstalling Avast did get me much more time between the reeboots.
The solution for me was anyhow to run sasser-removers, and getting updates from microsoft, not only those showing up on win-update.

//Ulti…

ps. Even though none of the sasser-removers found my systems infected, I’ve seen a few people being helped by running the removers anyway. Might be a good idea anyhow…