Distorted "Best" Multisample sound, and some drum

[lacaries]

I've had mi triton extreme for more than 5 years, everything worked fine until recently the drum kit sounds sound distorted... but only the drum kit sounds and certain instruments... what can be the problem?

* I've already restored the factory settings (made a backup)
* They sound distorted even with no insert effect or master effect
* It only happens with drum sound and some regular sounds
* The sound is distorted even at low volumes
* I recently changed the CR battery inside
* When I turn on the keyboard everything is fine, but after 5 minutes the problem starts.


UPDATE: The problem comes from the multisamples, when choosing categories (ROM, RAM, Piano, New1 New2, Best, etcc...), every multisample from the "Best" category is distorted...

Please help!

Thanks