Sounds like a pretty typical symptom of keylogging type spyware. Grab a copy of your two or three favorite spyware scanning programs, use each one to scan your system at least twice. You might be amazed the amount of garbage that Internet Explorer lets others put onto your system without you even knowing about it.
Be sure to keep scanning your system for additional spyware every week to month, lest this problem simply reoccur. Or you could stop using Internet Explorer for anything but Windows Update and stop a good portion of it dead in it's tracks. Not using Outlook Express stops even more.
Text jumps or hiccups up about three lines every so often in all programs. I have XP Professional and Office 2003. However, it happens in Dreamweaver, MS Internet Explorer and Netscape too.

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