This issue has been reported by K2000 and K2500 users. Updating the OS on the Kurzweil will fix the problem:
K2000 units need to be updated to v3.87, which is a hardware upgrade. Contact your Sales Engineer to determine which upgrade you need.
K2500 units w/o KDFX should be updated to v3.02
K2500 units with KDFX should be updated to v5.00
The K2500 OS updates are available for download from www.kurzweilmusicsystems.com.