Hi Ian,
I copied this from the below link. I hope this helps you...If not, you might
have to turn off sleep mode altogether.

Good Luck,
Phillip

http://support.microsoft.com/kb/930091

A Windows Vista-based computer does not resume from sleep mode if you move
or click a USB mouse as the computer is entering sleep mode
View products that this article applies to.
Article ID : 930091
Last Review : March 15, 2007
Revision : 1.4
SYMPTOMS
Consider the following scenario. You have a universal serial bus (USB) mouse
connected to a Windows Vista-based computer. You move or click the mouse as
the computer is entering sleep mode. Then, after the computer has entered
sleep mode, you try to resume the computer by using the mouse or by pressing
a key on the keyboard. In this scenario, the computer stops responding
(hangs) at a black screen.
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CAUSE
This issue occurs because some USB mouse devices do not work correctly with
sleep mode in Windows Vista.
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RESOLUTION
To resolve this issue, follow these steps:
1. Click Start, type device in the Start Search box, and then click Device
Manager in the Programs list.
2. In the User Account Control dialog box, click Continue.
3. In Device Manager, expand Mice and other pointing devices.
4. Right-click the USB mouse, and then click Properties.
5. Click the Power Management tab.
6. Click to clear the Allow this device to wake the computer check box, and
then click OK.


"ian00bell" wrote:

>
> Hello Phillip,
>
> The URL you referenced is no longer valid. Would you be able to post
> your solution?
>
> Thanks,
>
> Ian
>
>
> --
> ian00bell
>