Vista - Again "The Virtual Machine Monitor Driver required is missing"

Hi,everyone
I have met the "The Virtual Machine Monitor Driver required is
missing" error after a mysterious system clash.When I uninstall the
installer stopped and said "Some files of the application is used by
the Windows Explorer(Not Internet Explorer)", I can continue
uninstalling whether by ignore that or by end the Explorer Process use
the Taskmanager. But the VPC dosn't work when I finished the new
installation again with the same error.
I came here and found some similar problem reported but no useful
answer.
Anyone shall help me?
My system is Vista Ultimate with SP1 which was update installed from
XP SP.3. The "mysterious system clash" of host has happened the day
before yesterday. I shutted down the system normal after using a VM
machine, but when I switched on next the partition table has gone.I
have tried a lot and gotten it back finally,And "repairred the system
"with the installation disc, then got the system started, tried to
start the VPC, and then the error appeared.

On 5ÔÂ16ÈÕ, ÏÂÎç11ʱ52·Ö, taoeugon2...@xxxxxx:
It is seemed no one want to answer me hemm?
There's a special I found in this case: When you uninstall the damned
application the VMM.sys will stay.Is it meens there are something
using it still, say: Microsoft Device Emulator or somewhat?

On 5ÔÂ17ÈÕ, ÏÂÎç8ʱ32·Ö, taoeugon2...@xxxxxx wrote:I have it solved myself. It seems to be a problem of UAC, so you must
run the VirtualPC as administrator even if you logon used a
admistrator account.