Problems with sound and mouse stutters after upgrading to VIA Hyperion drivers v5.11A in Windows Vista (64) or XP (64)? Well, the solution is simple: revert back to v5.10A.
Is your problem the same?
Let me guess what kind of configuration you have:

You have a motherboard with VT8237A SATA RAID controller

You have connected an SATA harddrive (or more than one)

In your BIOS the controller is configured as RAID (instead of Non-RAID)
Right?

As far as I know, when in the BIOS the controller is selected as RAID, the V-RAID drivers are used under Windows, when non-RAID is selected the PATA/SATA driver is used.
The problem is in the V-RAID v5.40 driver. Support for new chipsets have introduced problems with the VT8237A chipset. The VIA Hyperion v5.10 package contains V-RAID V5.30C which doesn't has this problem.
So you actually have two solutions:

Use the PATA/SATA driver by setting the controller to non-RAID in the BIOS

Or use V-RAID driver v5.40
Well, I only could use solution 2 because when I set my BIOS to non-RAID the system wouldn't pass POST anymore (needed CLEAR CMOS).
Example downgrade V-RAID to v.5.30C in Vista 64
This example is for Windows Vista 64, but can also be used in Vista 32 and Windows XP (32/64), but another driver directory must be chosen.
Your situation should be: you have Hyperion 5.11A installed, have problems with it (sound stutter, mouse staggering) and are now going to downgrade the V-RAID driver from 5.40 to 5.30C. Right? Then continue? Not? Go visit some other site and just don't do it.

In the
device manager open
Storage controllers

Right-click
VIA VT8237A SATA RAID Controller and select
Update driver software

Choose
Browse my computer for driver software

Select
Let me pick from a list of device drivers on my computer

Click
Have Disk

Browse to the directory where you unpacked the Hyperion V5.10 drivers

Browse to
VIARAIDDriverx64 and select the .INF file (note, if you have Vista 32-bit or XP 32-bit you should select the winxp directory)

Click
open and install the driver

Reboot
Your problems should be history now.
Driver download
The drivers can be downloaded here
VIA Hyperion 5.11 drivers
VIA Hyperion 5.10 drivers