I had this problem last year with TT2017. Here is the post:
Same symptoms. I did an OS refresh and clean install, running Win10Pro on solid state drive. Spent over an hour with tech support, who was courteous and eager to help, but achieved nothing. He stated (and I believed him) that no one else had reported this bug. I will wait before running TT2018 to see if they finally deal with this. Best solution is to call CS and flood all TT boards with complaints. They may not acknowledge the issue, but they have to deal with it.
Before anyone dismisses my complaints, I have been using TT since taxdata 92. So spare me the advice about disabling AV. Good luck to all.