I don't know how relevant this is, but I'll put it here just in case:
Beware, latest Windows 10 Update may remove programs automatically - gHacks Tech News
(As always, follow that link at your own peril.)
I think there might be something to this, as after the last update I found that .pdf files were set to be opened by the "Edge" browser rather than Acrobat Reader. But that just might be me though.
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