I'm having some problems too with the kernel 2.6.14-1.1637_FC4. It don't reconize any PATA hardisk connected to my Promise controller.
I read that i could be because a recent change in the libata code and tried the trick:
to /boot/grub/menu.lst (Grub)
options libata atapi_enabled=1
But nothing seems to work.
Kernel 2.6.13 works as a charm, but it's getting something personal get that 2.6.14 working
Any ideas, experiences...