Dynamic Filling of CRviewer Problems

Hi out there,

I have a Report that gets its data from a database, and is filled by passing first a Parameter to a text field in the report that is later used to filter the records that come from the database
All that works well
Under certain circumstances the report has to be opened in multiple instances at the same time.
If I try this, the whole app crashes, when I try to open the report for the second time.
I checked - more than once :-( - if I forgot to kill the instanced objects (set xyz = nothing) in my code, but did not find anything. Still after opening and closing a report about 80% of the mem used by the report is still in use.
Is there an option for multi-instancing in CR that you have to set, or do I miss anything else?
Or is it a bug in CR?

Env is CR 8.5, SQL-Server 2k.