"Always use this program to open these files" is grayed out. Why?

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Track title: Puzzle Game 2 Looping

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Chapters
00:00 Question
00:43 Accepted answer (Score 31)
01:31 Answer 2 (Score 4)
02:00 Answer 3 (Score 4)
03:49 Answer 4 (Score 2)
04:04 Thank you

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Full question
https://superuser.com/questions/153465/a...

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Tags
#windows7 #windowsregistry

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