[AccessD] Strange problem with reports

Hi all,

I am having a strange problem with reports in an Access 2003 application:

The app is running on a Citrix Metaframe XP server. The report is opened in
print preview. If I change something in the page setup (e.g. paper size or
margins), an error message shows up when the report is closed or saves
(CTRL-S):

'You can't set the Event Proc Prefix property in print preview or after
printing has started.
Try setting this property in the OnOpen event.'

None of my code tries to change that property.

What could that be?

Michael