It may help, Hun, if you were to use the left arrow to go left and the right arrow to go right...
<== Left
Right ==>
It does it for me too, sometimes and I've found a fix is to mess with the cycles until the game runs smoothly.
The number changes depending on the machine, so try changing dosbox to use % cycle changes (lower than 500 step, but I prob don't remember that correctly) and see if it helps you, as it has me.
[oh yeah]
I'm making maps for this and Kyrandia bits in Excel - I'll transcribe them when complete. Give me a while...