Vista - Unable to enter standby/sleep mode with x64 Vista

Well I have tried looking for a solution on the net but so far drawing a
blank. Perhaps someone has figured this out and can help me?

I reciently installed VISTA Ultimate x64 (clean). Everything is working
fine, except when I attempt to send the computer into sleep mode (S3). The
computer thinks for about 5 seconds, begins to power down, and just as it is
about to sleep, the fans and neon, instead of powering off (as they did with
no issue in XP), blink and the system begins to power back up.

I tried disabling all of the "Wake from sleep" on USB mouse and Keyboards
and I have downloaded and installed the USB Stack issue/update. I have tried
modifying the power settings (balanced, Max, Min and CUSTOM) but with no
success. The computer keeps hitting the sleep mode and then powering back up.

I have double checked my BIOS and I am in a S1/S3 state. I have ACPI 2.0
enabled.

Any suggestions on how to fix this issue so that I can get VISTA to enter a
full sleep state?

Specs:
AMD x2 4800+ / 1Gig TwinX-4000PT / Asus A8V Deluxe
Windows Vista x64 Ultimate
USB Keyboard (wireless) / USB Mouse (corded)
SB Audigy 2 ZS / Winfast Leadtek 2000XP Expert

Exactly the Same Pb here...! x32 Ultimate edition of Vista... Any clue ?
Thanks!
P 3.4Ghz
2Gig Corsair
ATI X1800XT 512Mo
Asus P5GDC deluxe

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