fileIO ERROR_SHARING_VIOLATION when compiling with TexWorks from MiKTeX 2.9.5721

reactOS 0.4.7RC1 on VBox 4.3.40

MiKTeX 2.9.5721
SHA1: aa96e28bcd66a4da6644aa1fe06c6e827469394f
from
https://www.heise.de/download/product/miktex-288/download
or
https://chocolatey.org/packages/miktex/2.9.5721
was the version I came most far until now.
(2.9.5105 failed earlier,
2.9.6361 and higher are Vista+)

Setup succeeds.
TexWorks starts up.
File / New from template / Basic Latex Documents / article.tex
Click the green compile button top left, process will start, but fail because
initexmf process fails with
Windows API Error32 ERROR_SHARING_VIOLATION The process can not access the file because it is being used by another process.
047RC1-mt-issue.log
047RC1-mt-issue.png