testing Internet Explorer 9 on virtual PC

Solution 1:

You don't say where you downloaded this image but I guess you downloaded it from Microsofts Internet Explorer Application Compatibility VPC Image. If you scroll down on that page you can read this line

The password to login to all of these images is Password1 and the username will be present when you first login

Solution 2:

Note the new password might be

Login Instructions
Login Information (for Windows Vista, 7, 8 VMs): IEUser, Passw0rd!

If you downloaded from http://www.modern.ie/en-us/virtualization-tools#downloads see https://modernievirt.blob.core.windows.net/vhd/virtualmachine_instructions_2013-07-22.pdf

Solution 3:

Here it is: Passw0rd! As the following image shows: