A very interesting thing happened recently.
McAfee, a 'leading' anti-virus software developer, sent out updates that recognized major commercial software as viruses. For example, it marked MS Excel as a virus. Consequently, users that had selected 'auto-delete' as their default option, suddenly found that Excel and a host of other programs were not available.
This is professional hara-kiri for an anti-virus software. I use McAfee and I was afraid to log into the administrator account of my laptop (updates are only installed when you login as the administrator). To be honest, I still am. Thankfully, I did not have many programs installed.
I'm sure this has severely reduced the trust that people have on McAfee. Moral of the story:
Always QC your deliverable.
More details of this can be found in
this article from ZDNet news.