Ok, I kind of solved the problem. I mean, it's working today. But, why didn't I submited the solution?
Well, I'm not sure what happened, so I can't tell you exactly what to do, and if I submit something like this I could generate more doubts about this.
But I'll tell what happened. Here the main problem was that the php dll that accesse oracle was incompatible with installed oracle client. The solution? I tried to install another client, and another, and another... I couldn't tell you for sure which client worked, but it worked.
Later, I had problems with a specific oci function, I downloaded a new .dll version that was incompatible with my client, then I installed other oracle versions.
Why I don't care about this mess? This was temporary, I solved this within 2 days and then I could use my temporary research server for a month or two, now it's not even installed.
Conclusion. If I had used linux I wouldn't had this problem. The whole problema was about incompatibilities between compiled dll and oracle client versions. My advice is "Forget about Windows"