After clean install of Ubuntu 15.04 it could be confirmed that problem continues to be present.
After switching to upstream kernel 4.0.9-040009-generic #201507212131 problem has not been seen for a few weeks.
After clean install of Ubuntu 15.04 it could be confirmed that problem continues to be present.
After switching to upstream kernel 4.0.9-040009- generic #201507212131 problem has not been seen for a few weeks.