Hi guys, thanks for bringing this issue to us. We've been analyzing the upcoming Avast 2016 version and we've found a place where this phenomenon can occur. It is related to the C++ Boost library, which exhibits this unwanted behaviour in certain waits/timers. Boost has already confirmed this to be a bug and fixes it in the next release.
We have updated the code not to use the said timer from boost, however it seems that this specific case was limited to the Avast 2016 Beta only.
Since y'all report this problem with 2015 R4, we'll continue searching.