Thanks for the hints folks, @Amigaharry2 - I have not that CF2IDE hardware, usually when I need an emergency/recovery boot I simply use the MOS installation CD though. Anyway, I don't think my system reaches the loading stage of boot.img, because when this issue happens the monitor remains in standby mode, which is still a very early stage AFAIK. Also, when this happens I think I can't hear the noise of the HD spinning, that's why I suspected it was related to the HD
@koszer: no, no sounds and no blinking
@zukow: uhm ok I still have the ASD image to burn, I will check as you suggested. I will also try to swap the CPU modules once I have some time for it.