Opening MS Virtual-PC 2007 *.vmc files?

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    Why does the VM Player, which I just downloaded to this WinXPpro machine, abort with error when I ask it to open either of my two functional *.vmc files (one is Bart-PE-XPpro, the other is Win-98se)? Is there anything I can tell it so it understands them better? I tried to help it by using VM Converter on them, but that didn't work either. Seems very strange to me, isn't this stuff supposed to be very good? Any help will be much welcomed. --G