Windows 7 Virtual PC will not start and just stays powered down - No errors, or event logs

"According to this Virtual PC Guy's Blog:

It seems that people are constantly
running into problems running Virtual
PC on laptop systems with advanced
power management. The reason for this
is that Virtual PC is very demanding
on hardware and has very strict timing
requirements - and as each new
revision of laptops comes along these
systems perform more and more complex
power management.

Problems start happening when these
laptops tweak with things that we rely
on. This can either be caused when
the laptop changes the CPU frequency
too often, or when the laptop actually
powers down sections of the system
that we are dependant on in order to
conserve power. When this happens the
user can see a variety of problems;
ranging from sporadic pauses and
bursts, virtual machines running too
fast or too slow, repeated keystrokes
or missing keystrokes to other timing
related problems.

While I don't suggest following the suggestions in this article, the explanation might hold true.

The single biggest eater of CPU resources is probably Aero. You may test turning Aero off to lower the power demands, and seeing if the problem disappears.

In case it does, you may set Aero to turn off automatically when and only when VPC is run, by right-clicking its executable, choosing Properties / Compatibility and checking “Disable desktop composition”."

"Can this be a problem of compatibility with Windows Virtual PC?

Under Windows 7, XP mode is supported via Windows Virtual PC.
If you have installed ""Virtual PC 2007"" on your computer, then this article seems to show that there are problems when Windows Virtual PC is also installed on the same machine.

What's more, the virtual machine formats of both VPC versions are somewhat different, so a VM created with the one can't be used as-is on the other, per this article."

Take in to consideration that Virtual PC and Windows Virtual PC are two different products. Do you have Virtual PC and trying to run XP mode under that? I believe that that won’t work.

I just tried the same, mine is W7 Ultimate, XPmode works fine. The installation starts, but it stops after the 2nd prompt with some kind of graphic error. On the Windows Virtual PC it shows as powered down.