Sleep States

I am trying to run HCT on my driver. It is using the unclassified/universal
package. The driver verifier parts of the test fail on all systems I have
tried. If I use WIN2003 and the 11.2 HCT, I get the following:

198.1AC : +VAR+SEV2 0 : There was an error detecting parameters for
test ACPI S1 Stress
198.1AC : +VAR+SEV2 1 : There was an error detecting parameters for
test Enable/Disable - Device I/O

If I use WINXP and 12.0 HCT, the message is different, but very similar:

1A4.1C0 : +VAR+SEV2 0 : There was an error detecting parameters for
test ACPI Stress
1A4.1C0 : +VAR+SEV2 1 : Error: The detection function returned the
following error: 'Desktop Systems must support the S3 and S4 sleep states.
Not all of these states are supported on this system.'
1A4.1C0 : +VAR+SEV2 2 : There was an error detecting parameters for
test Enable/Disable - Device I/O
1A4.1C0 : +VAR+SEV2 3 : Error: The detection function returned the
following error: 'Not enough storage is available to complete this operation.
'

The system has 512megabytes of memory. It can be "suspended" instead of
simply powered off. It claims to support "hibernation" in the power options
properties of the control panel.

How can you tell if a system supports a given sleep state? Is there a way to
change this with a utility (control panel?) or registry setting?

How much memory does the enable/disable device I/O test require?

Are these real errors? They don't seem to have anything to do with my driver.