Text disappers when writing in any office application

Hi

We have a user on Office 2007 that has come into work this morning and can
not complete a paragraph in Outlook/Word with out half of it disappearing
before he finishes.

I have ran the office diagnostic tool and it has flagged nothing, I have
made sure the overtype rule isnt on and have unistalled and reinstalled the
office application and still it is present, although not in other programs
such as notepad etc, which leans me towards thinking its an office issue.

any one any ideas's? thanks.