I got a similar call where the caller said "Hi, I am calling from the internet(!), your computer has lots of errors, we need to look it up". as soon as I asked him "which IP has he got the problem with" he hang up.
My husband got the 'Microsoft' call, on which he replied: "So as you are calling from Microsoft, you know who you are calling, don't you?" The guy replied "no" on which my husband said "I am the Marketing Director of Microsoft UK" (he is not), and the caller just hang up.