At my work we use Office 2003 and up along with different operating systems. The issue I am seeing with one of my co-workers outlook is with windows 8.1 and office 2003 (Yes I know that's an odd combination)

Normally when composing an email the user can type in the address in the "to" box and names will automatically populate and then the user can select the name for the list.

The problem is not with the autocomplete that works fine the issue is once an email is autocompleted and you go down to select it from the list it will not fill in the to box. meaning if I were sending an email to jack@gmail.com
I would start typing ja
and then jack@gmail would come up. when I go down to select jack@gmail.com and press enter or double click or anything it goes right back to ja.

I cannot seem to find an answer to this issue, I have tried detect and repair as well as scanpst.exe

Any ideas? thanks in advance.