I should maybe apologise for asking a misleading question in the first place - I thought CCCP had "installed" Haali but I realise now it had only registered the specific filters. So apologies if I took the query in a misinformed direction.
I'm no developer, and you haven't had chance to reply to JEEB yet (who I believe is), but...assuming that AVStoDVD can call directly on the filters I assume that ideally the AVStoDVD installer would, as JEEB said, check for the filters which AVStoDVD may require in use and uncheck Haali installation if already present. Is that a possibility for future release, Mr.C? I'm surprised this issue hasn't come up before actually - maybe no-one realised there was a conflict!