There is a known issue with this beta driver if this driver is installed when the Miniport driver v3.20B is already installed on the system.

This driver supports Windows 2000, Windows XP and Windows Server 2003 only. Legacy Microsoft Operating systems are not supported. This driver will increase performance of ATA hard drives and ATAPI devices (such as CD/DVD/combo drives etc). This driver may be used with any VIA chipset. Further information is contained in the Readme file. This driver is currently only available in this individual package. VIA IDE Accelerator Driver 1.21 Beta Windows 2000 XP 2003 will however, be included in a future release of the VIA Hyperion 4in1 driver package.