Legally, I doubt either Open Source programmers or Microsoft can be held responsible, provided that both of them release their software under licences and user agreements that absolve them of any responsibilities. Morally, Open Source programmers cannot be held responsible because they give you the source code, so even if they release crap (yes yes I know crappy OSS is unheard of) it's up to you to ensure that it works correctly. MS on the other hand sells you a product that you cannot fix, so they are completely, morally, responsible for any problems caused by poorly designed software.
Same type of real world relationships, same time vacuums, same same.
Legally, I doubt either Open Source programmers or Microsoft can be held responsible, provided that both of them release their software under licences and user agreements that absolve them of any responsibilities. Morally, Open Source programmers cannot be held responsible because they give you the source code, so even if they release crap (yes yes I know crappy OSS is unheard of) it's up to you to ensure that it works correctly. MS on the other hand sells you a product that you cannot fix, so they are completely, morally, responsible for any problems caused by poorly designed software.