Oops

I was supposed to have four threads left over when I’d done threading this warp.  Hmm.  Six.  
SIGH.  Still Not Perfect!
With 764 or so ends in the warp, a fairly straight forward but ‘fancy’ 16 shaft twill, I have no idea where the error is.  So I have sleyed and tied on and am now trying to find the mistake.  And it’s hiding.
In the process, I discovered that the computer that runs the loom has suddenly disappeared ALL of my weaving files – except for the warp I just finished weaving.
There are days when I’d really like to hide in a blanket fort with a colouring book.  This is one of them…
Edited to add:
I spy with my little eye…two empty heddles just to the right of the red thread.  The solution is ‘easy’ – add two spools of the warp thread, enter them into the empty heddles, which is where they belong, obviously, move the rest of the threads ‘over’, re-tie and continue.  
After lunch.