Marc, I've used Symantec/Norton Ghost and Acronis Disk Director to repartition drives many times, I've never had a 'lock' situation, I don't think it's possible. It might be that you cannot resize the active boot partition while you're booted from it, or that you have to reduce the size of the 2nd partition (of the new drive) 1st before you can extend the boot partition into the new free space. Also, have you tried booting from a CD and then run the partition resize?
Acronis let's you resize from the active boot partition.
-N