I wouldn't have believed it if I hadn't seen it myself.

A coworker's computer seemed possessed today. It would start typing a few words of gibberish from time to time into applications. Stuff like "the inferno Irish firefly ravishing purple bulldozer."

A bunch of us crowded around to watch -- it got weirder and weirder. Thinking that his computer had been hacked and an intruder was doing this, the admin pulled the network connection to his computer.

It kept on going.

We downloaded AdAware; nope, no spyware found. Virus checks found nothing. It truly seemed possessed.

Finally, we realized that it was only happening in Internet Explorer and various Office applications. After a bit of searching -- through Mozilla, which was unaffected -- we found out that it was the speech recognition engine, installed by OfficeXP, going haywire (details here).