Links in Outlook go nowhere

Hello I raised this issue a while ago but didn’t get anywhere.
I have a number of NT machines with Outlook 98 on which when typing links to files on the network Eg;- \\man\doc\doc.doc. Outlook doesn’t recognise this as a file and link to anywhere and just leaves it as txt/ If the File: is used it is ok and links fine. The editor is set to Rich Text and seems to work fine on some install and not other with no good reason.
I am thinking file associations or a registry setting somewhere any body with any ideas???