PDF to DAT Problem NT/XP & R5/R6

This problem is similar to a couple of others already posted, but with a twist!

We are currently upgrading our users from WinNT to WinXP, R5 to R6.

The user receives pdf attachments from an external source. When these attachments are viewed on her “pre-upgraded” (NT4/R5.0.12) machine there is no problem. However, when viewed on her “upgraded” (XP/R6.0.3) machine she sees the same attachments as (e.g.) atth1xg4.dat. i.e.

NT4/2k & R5.0.12 - seen as pdf

XP & R6.0.3 - seens as dat

Her mail file is stored on our server so she is looking at the same database in both instances. Can anyone suggest where the problem may lie? OS or Notes Client. Better still, can anyone suggest a fix?

Thanks in advance,

ST