We're sorry about the poor experience. We are investigating a similar issue. Is this happening with any specific project or all the projects? Also, do you have nested clips in your sequence? Let us know, we're here to help.
I have been having a horrible time with Adobe Premiere Pro. It is generating errors when I try to expor files. I cannot export .Mov or Mp4 files. They come up as rogue files that cannot be opened. Adobe has yet to give me a fix even when I contacted support.