Hi Thomas,
That's odd, it works on mine. Do you have the right bit version for the o/s you are trying to install it to?
The reason Disk Management has those limitations is to stop users getting into trouble.
If you expand the System partition to the left (into the lower address spaces) - you lose the ability to boot.
You can use the Paragon to do it, but will need to run startup repair to correct the bcd entry afterwards.
Or, use the Paragon "Copy partition" function to copy the C partition into the unallocated space - the Paragon will create the bcd entry for you.
Then mark the new partition active, delete the C you have now and extend the new one to the right.
NOTE: When copying a partition, the unallocated space needs to as large or larger than the source ( obviously) - so you may want to shrink C a little before copying it.