Thanks very much for the testing, I've re-written how the cursor sprite is placed, before it was being moved manually whenever an action happened (I was being lazy...) so it was possible for its screen position to get out sync with the selected cell. I now have a lookup table to re-position the cursor every frame based on the row/column of the selected cell.
I think the score glitch is because the score uses binary-coded decimals, when any component of the score calculation is more than 9 it's putting the total out of BCD range. Should be an easy fix.