This error occurs occasionally  and it usually just means that a key a hit too fast and the program couldn't recognize it. It is also called a "lose focus" error meaning windows lost focus of the cusor and couldn't keep track of it.

There are rare cases where this error is caused by a bug in the program. If the error can be duplicated repeatedly, it is likely that this is the case and you will want to report it to KSS Tech Support.