[al2o3cr]

    And let's not forget about the fact that the file you just
    created might not be readable or writable the next instant
    because some other process (usually some sort of
    "antivirus") decided to open it in a exclusive mode.

THIS. Spent quite a long time trying to reproduce a Windows-only bug with the old Rails 2 gem unpacker caused by exactly this; the code would create a directory "foo-1.2.3" and then immediately try to write files to it and fail because of an exclusive lock - on an empty directory.