Virtual PC Integration Features Not Working

I was not able to use my integration features on my Virtual PC. This is what was happening:

The VPC would boot up and immediately grey out the "Enable Integration Features". I was unable to click on it. I tried restarting but that did not help. Sometimes when starting up the screen would just be black.

The solution was to shut down the VPC and then delete the *.vmc and *.vmc.vpcbackup files. I then create a new VPC and attached my *.vhd to it. Started up the machine and I could now enable the integration features.

My host machine is Windows 7 64-bit and the VPC is Windows Server 2003 R2.