Outlook/Word problem with locking up

Have a coworker who has recurring problem while typing MS Outlook 2007 messages. Coworker says the mouse disappears (which he describes as mouse cursor going to the bottom of the screen without human intervention) or he gets the hourglass and gets “hung up” while typing messages.

His machine is set up with Word 2007 as the email editor. Using hosted MS Exchange email, but the messages download to the desktop, and the connection with the Exchange server is working.

He is the only one this is happening to.

I don’t see this issue occur when standing over his shoulder trying to replicate the problem. We’ve been through service calls with the Exchange hosting service.

He is not a crackerjack typist. Is there some combination of accidental keystrokes that could cause this? He does know enough not to CTL/ALT/DEL in the middle of typing a message.