Sound mod install error.

[Vanquisher]

I've been using the latin voice mod and the cc-light music mod on RTR, vanilla, and Darthmod untill now and i've never had any problems. Ever since i've started making a new mod, i've found that installation of any of these files fails to work properly. Here are the details:

a) Sometimes I install the cc mod and the music plays fine, but no unit related sounds at all.

b) If I install the Latin mod, units won't speak as individuals, but drag-selectinng them, they do.

c) I've tried installing them into vanilla versions again, but i get the same problem but only with the latin mod.

d) I've also tried copying the working sound folder from RTR and using that, along with txt. files of course, but the same problem.

Does any-one have any ideas on what is going on? I have a hunch its something stupid and noobish, but all this modding losing me sleep so I think I may be missing something fundemental. I'm sure i'm doing exacly as before though.

EDIT:
I've just started playing SPQR and have the same problem, without any modding. It has to be something to do with sound drivers maybe?