I had this problem too, and I think the following fixed it:
1. Run EFI installer 1.1, click custom install and select "Remove custom dsdt.ami file". Reboot. Wait, it loads quite slowly.
2. Run EFI installer again, reinstall PCEFIV9 bootloader, Dell Mini 9 extensions, Hide DellEFI files, Generate custom dsdt.ami file, Restore the 10.5.5 keyboard pref pane, enable remote CD, fix bluetooth.
3. Remove the power cable so you're running on battery power. Reboot.
Removing the power cable seemed to be a critical step - I'm not sure why.