Hi everyone,
I had exactly the same problem. It seems a simple "service wpa_supplicant stop" is not enough to actually stop all wpa_supplicant processes. It still keeps running.
As a short workaround I just killed the process and after that hostapd worked fine :-) Now I just need to find out where and how to configure the networking, so that the wpa_supplicant is not started at all...
Regards,
Motlib