Do not worry, it is not a malfunction. You have the K2vx sound roms installed, which gives you the same programs as the K2500. Included on the chips are the instrument names for the 800 and 900 Orchestral and Contemporary bank. If you do not have these ROMs installed, many of the samples they reference simply do not exist in your machine so you may get random noises or silence from these programs. However, a few of the programs function fine because they use the K2000 built-in samples. This is normal operation and will not cause any problems.