OCX build with CB3 doesn't work in MS VC 6 apps

Hi,
I created a TActiveForm based OCX with CB3.
This OCX works fine when using it with VB, Word, MMC, or the MS
Testcontainer. But when I embed this control into an MFC based
application the app uses 100% CPU load as soon as I double click
the Reportview in my control or select an entry from an contextmenu
of the reportview. Other OCX controls (written with VC/VB) work fine
in these MS app. It also freezes if I simply try to test the dialog
in VC6.

Thanks in advance Markus