This may mean that the Intellistitch is registering an obstruction and is giving a more powerful pulse to the needle. First, inspect and clean your track and wheels to make sure that there is no damage. Also inspect the o-ring on the encoder wheels. If you do not find any problems there, check your motor brushes to make sure they are not worn down below 3/8". If you need new motor brushes, they can be ordered from www.quilttech.com.
This problem could also be due to a power surge. Check that you have a functioning surge protector on your machine. Try also plugging the machine into another outlet if possible.