Had a strange fenomenon in a vdi environment. Users started reporting that when they opent Internet Explorer it would flash open en close. in the taskmanager you could see the processes stacking up everytime a Internet Explorer was started. To make it even stranger Explorer was also giving a error when opening it couldn't access the path or find the path. To make it even worse Microsoft Word started to act up also. The first sings began when the migration of domain controllers from 2012 began to 2016. With many DC's a oilleak began to spread and more and more users started complaining. Also on local clients error's were reported. It turned out old migration userhistory sid's were the problem. After they flushed all the sidhistory the problem was gone. We did a lot of google searches but didn't find this one yet.