The scenario goes something like this:
One day while using your XP system suddenly every time you start typing Outlook opens! Every few keystrokes it opens and gains focus, again and again. “What in the world is going on here,” you think. “Perhaps a virus!” So you fight with the errant machine and eventually start a virus scan, coming up with nothing unusual. Checking for spyware or other malicious programs also comes up empty. But the obvious and annoying problem persists. “Must be something hard-core. I have no choice here but to reinstall.“
So after partitioning and reinstalling and praying, the system comes back up again, only to have the exact same issue!!! “How can this be??? I wiped that sucker CLEAN!“ you think.
This is the exact experience of my brother in-law. And we tracked it down to of all things a shoddy keyboard:
The thing that tipped us off was that we noticed that Outlook would only pop up whenever he started typing. On newer Microsoft keyboards there's buttons built-in to call up your mail application (and browser, calculator, Windows Messenger, etc.).
These keys get automatically recognized by XP. No need to install a specific driver to activate them. So the junk keyboard was sending over the same scan codes as the email button about every other keypress. Very annoying!