They've made some changes in the PCI database that you should be able to work around with a custom simple.map file. The first list is from update 2 and the 2nd is update 3. You'll see that they've started using the IDE driver instead of ata_piix. This is likely to do with the fact that the ICH7 controller is now supported in IDE mode for use with SATA CD-ROMs.
8086 27c0 0000 0000 storage ata_piix 82801GB/GR/GH (ICH7 Family) Serial ATA Storage Controller IDE
8086 27c1 0000 0000 storage ahci 82801GR/GH (ICH7 Family) Serial ATA Storage Controller AHCI
8086 27c3 0000 0000 storage ahci 2801GR/GH (ICH7 Family) Serial ATA Storage Controller RAID
8086 27c4 0000 0000 storage ata_piix 82801GBM/GHM (ICH7 Family) Serial ATA Storage Controller IDE
8086 27c5 0000 0000 storage ahci 82801GBM/GHM (ICH7 Family) Serial ATA Storage Controller AHCI
8086 27c6 0000 0000 storage ahci 82801GHM (ICH7-M DH) Serial ATA Storage Controller RAID
8086 27df 0000 0000 storage ide 82801G (ICH7 Family) IDE Controller
8086:27c0 0000:0000 storage ide
8086:27c1 0000:0000 storage ahci
8086:27c3 0000:0000 storage ahci
8086:27c4 0000:0000 storage ide
8086:27c5 0000:0000 storage ahci
8086:27c6 0000:0000 storage ahci
8086:27df 0000:0000 storage ide