thanks for the cpr file.
1)you have slot 7 set to omni with a NES chip loaded in it (so it plays whatever channel 3 receives as well (ie your bass line)
2)Slot 7 has pitch eg set to +4800 cents, effectively boosting it two octaves higher.
if you don't use slot 7 i suggest emptying it.
Dont worry i'm overly sensitive about bug reports, especially when i cant begin to think how that bug can be possible