This issue has plagued me for several months so I finally decided to do something about it.

Virtual PC 2007 used to work fine when the console was opened, all was well.  Suddenly and without warning, I would launch Virtual PC and the Console would no longer appear.

The Console was still accessible via the system tray as shown below:

From here you can right click and use the console options.  However the Console window is nowhere to be found. 

I applied SP1 when it came out but this did not resolve the issue.  I also tried reinstalling the software to no avail.  Here is an interesting fact:  I connected an external screen one day when I was working on presentations and low and behold!  The console was there...

I was ecstatic!  The next time I shut down the system and started it back up guess what?  Lost again...

I started searching on this issue and located an article discussing a .NET issue and the options.xml file.  I had a .NET issue as well in my event logs so I figured let's give this a shot. 

I backed the file up first before making changes.  Also, Virtual PC must be closed or you cannot save changes to options.xml.

In Vista, the file is located under: C:\users\%username%\appdata\roaming\Microsoft\Virtual PC\

Here is what I found:

So I modified the <left_position type = "integer"> to 10 as well as the <top_position type="integer"> to 10.

After saving the file, I started Virtual PC.  Bingo!  Problem solved.

Here is the latest options.xml file after moving the console around the screen a bit...

Read the complete post at http://owsug.ca/blogs/brad/archive/2008/09/02/Virtual-PC-Console-seems-to-have-disappeared-and-will-not-display.aspx