Here's a problem that plagued me for months until the light bulb went off in my head. The problem is that for random applications, usually outlook, but sometime IE, Netscape, seemingly random words would get input while I was typing.

I was paranoid about viruses, and ran virus scanning with negative results. Besides, I very careful about opening attachments.

I was paranoid about a crackers, and so ran a network sniffer looking for odd traffic and again, negative results. Besides, I've learned the hard way to use a firewall, so it seemed unlikey.

My PC has a microphone on it, and after several months of getting annoying prompts from outlook to train the pc for speech recognition, I decided to try it. Saw, grabbed the microphone, and quickly determined that speech recognition on Windows XP would be at best a large investment of time. So I left the microphone close to keyboard and then proceeded to use outlook to compose a message. Then the random word noise heated up. I realized then that voice recognition was interpreting the random noise in my office has English words.

So I removed speech voice recognition (go to control panel -> settings -> regional and language -> languages -> details -> speech recognition and then click remove).

Things seem to be better now.