I upgraded my 64bit 10.04 install, and now linux refuses to boot. It can't find the hard drive, and there's what appears to be a stack trace from the kernel with lots of AHCI references. It then complains about not finding the install drive and drops to busybox.
I proceeded to download the 10.10 64bit iso, and during boot from the CD the same problem happens.
Oh, it actually looks like the problem is in modprobe. first line in Call Trace is ahci_deinit_port. after the trace it says '/sbin/modprobe -bv pci:vxxxxx' unexpected exit with status 0x0009.
This is a Dell T3500 workstation. I can't disable AHCI, since I think that will hose my Windows install.