What on earth are you on about? Michael makes no mention of an OS upgrade.

It is not that rare for a hotfix, which may be automatically installed, causing problems. Just the week before Christmas (and naturally on the day of a major release) our IT department downloaded a batch of some 50-odd MS-supplied fixes and as a result our build servers started crashing. Personally I have never had that happen with the Office suite, but I have had it often enough elsewhere that it wouldn't surprise me.