Kurzweil k2600r "cc cram index 43 error 1873"

Hi guys I have a problem with my K2600R and can’t figure out what’s wrong.

Does any one have idea what this “cc cram index 43 error 1873” is about? it just randomly happens when I change preset on program window. and also it randomly turns back when I enter any other windows such as Disk window or effect window. all Ram test on Diagnostics was fine and couldn’t get any clue what thiis is about.