UPDATE: I decided to go for it and reduced the partition on the destination drive. The system wouldn't do a warm boot - just like before. But did a cold boot when I cut power.
So now it seems that I'm OK once again - at least I hope so. My destination drive has been going nuts since the reboot. I have no idea what it's doing. Plus when I do a DIR of my C and destination drive (E) I get a different result. IOW, there are more files and unknown stuff on the E drive. I thought they should be identical. Meanwhile the E drive hasn't stopped chirping since the reboot.
I should replace the C with the E and see if it boots.
I have just one last question:
How can I determine the actual size of a hard drive so I can now make my destination drive the same size as the source? I'd like them to be interchangeable.
Thank you, thank you, thank you! All of you. You saved me.