Since installing gpg4win 3.0.0 I've had a number of occasions where outlook (Office 365) appears to stop working. Copy/Paste doesn't work, send doesn't work, opening emails doesn't work and some other stuff and, when I change folders in Outlook, it will show up the message:
"cannot display the folder. out of memory or system resources."
When I uninstalled gpg4win/GpgOL this problem went away.