My girlfriend's phone had exactly the same problem, the same error and the same messages on screen.
I spent hours on blogs and, when I was almost giving up, I found out a solution.
To tell you the truth, guys, I used the same procedure on my dead moto quench (cliq xt) five years ago... it seems stupid, but I've almost killed myself trying to do something to recover the fastboot which i thought was the reason... I was wrong...
So, here's what I did to solve it:
1 - First, have the motorola drivers and rsd lite 6.1.4 (or a higher version) installed;
2 - Download the version you need - sbf.droid-developers.org/phone.php?device=13 - sorry I cannot include the address here 'cause I didnt reach 10 messages on xda = P
3 - Unzip the file and edit the .xml file with notepad. It is the only .xml file on the folder;
4 - Remove the whole line which contain "getvar" word. (It must be the fourth or fifth line);
5 - Save and close the file;
6 - Now you can flash normally with rsd. IT WILL NOT STOP ON 8/12 STEP ANYMORE;
Please try it and post your comments;