Related in some way, I think... I definitely remember having problems with a specific PC configuration that was solved by disabling HT in the BIOS and then reinstalling Windows XP, and AHCI (I think) was the culprit!
Perhaps you were thinking of 'ACPI'?
For the record, 'AHCI' relates to SATA interface mode and has nil to do with HT, while 'ACPI' is a BIOS system auto-configuration mode which is necessary for HT.
(Not trying to set a record, just to set the record straight)