Reply to my e-mails from Lotus Notes users fail to show their comm

This is very strange!
The problem is that my HTML formatet emails, returnen from an Lotus Notes
user, shows exactly like the email I originaly send. Any comment made to the
message by the Notes user is gone.
I'm not using an exchange server!
When I check the mail on my Webmail account, before collecting with Outlook,
the comments is pressant.
The problem is seen from Lotus Notes users on at least 3 different Notes
servers.
And here comes the very strange thing; From one Notes user, the problem is
never seen, but an other user using the same Notes server the problem shows
every time!
I'm using Outlook 2007 on Vista. All updates is installed!
The problem did also show when I used Outlook 2003 on Windows XP.
I have not been able to find anything about the problem og the internet. Am
I the only person in the world that has this problem? And om more than one
installation!
Does anybody know if I can make a change to my configuration that solves the
problem?
Regards Steen