Jazzmammal, you're right when you say that Asio4All is not ASIO, sorry for that. Other than that, it seems (with all my respects) that you haven't read my previous post: Asio4All (wich is not a "freebie", but a serious and very widely used ASIO driver, btw) works perfectly well with other programs, at least in my system, and it seems (I gave the arguments in that post, but of course I can be wrong) that the problem is due to the way BIAB handles ASIO drivers and MIDI Out ports.

Anyway, the solution given by Kent works, it solved my problem and it's a good workaround. If PGMusic decide to address this issue on future versions, I'll be happy; if not, I'll be happy too. In the meanwhile I'm not going to dump my lovely Alesis Multimix, it works really well and I'm very happy with it too!

PS: Yes, I'm using a modern computer (Core i7, lots of RAM...), I'm up to date, etc, etc, etc...