Vista - Hanging Vista

There are thousands of Google hits on this subject but nothing specific in
the Microsoft Knowledgeless Base, which tends to never have answers to
common problems.
If Vista, 32 or 64, is deliberately put into sleep mode or goes there when
unattended according to whatever power settings are on the machine, Vista
will then hang indefinitely when shutdown unless the power button is used on
the computer. BIOS settings seem to be irrelevant when checked.
This can be seen with a fresh install, on different machines, with a wide
variety of software/hardware. both 32 and 64 bit Vista, before and after SP1
and other updates.
I personally see this more on desktops than laptops and more on Vista 64
than 32 but there are many, many Google hits about laptops and Vista 32.