This can come up even with application software (which is my area). If it worked before and it's broken now, or if your application appears to be the only thing that is broken for the user, from most user perspectives, it doesn't matter that the problem may have been technically created by an OS bug, errant virus scanner, or whatever. As I tell colleagues, "It may not be our fault, but it's still our problem."
Correct. Customers are paying for a working solution. If what they get doesn't work, they couldn't care less (and shouldn't have to care) about who or what is to blame. They just want it to work.
