I was working on some project inside Eclipse. Suddenly I saw an error on Eclipse project and no clean or rebuild worked anymore. Inspecting the error I saw that my output build folder cannot be deleted because is used by other application.
I closed Eclipse and I tried to delete the folder manually, but Windows could not delete it either. I opened in windows resmon.exe and inside CPU tab / Associated Handles I searched for folder path.
I found an entry with an OUTLOOK handle to that path. Why? Just because I sent a mail with a file from that path.
Evil OUTLOOK is so buggy!