Opening interaction template launches installer

We have Navision 3.70B. On a recently purchased machine running Win XP with SP2, whenever we open an attachment in the Interaction Templates of Relationship Manager, the Navision installer launches. It can’t complete, so it errors out and reverses and then soon after this, Microsoft Word 2000 opens with the attachement on the screen. No other machines do this, even other ones running SP2. Navision itself opens without a problem from a desktop icon. I can’t tell if this is a word problem, a navision problem or a windows xp problem. On this machine, it does it whether I log in as administrator or a plain ole user. thanks curt