DLL conflicts ?

I'm having some issues with the Modules directory in FS2004 and I recall reading something about a DLL conflict with other 3rd party add-on AC.I think it was a PMDG 737 or 1900 series and a Flight1 727 dreamfleet product, but I've seem to have lost the link and the readme/web sites aren't listing any specific incompatibilities.No blame here, just trying to discover what two AC are conflicting in my system.Thanks, Rob.