Is is digital? Or tape?
If it's tape, the needle or the tape is slightly out of place, causing friction, and making a squeak.
If it is digital, it could be one of many things.
~ You could be talking to close to it.
~ The recorder box may be off. (Did you ever drop it?)
~ The battery might be low.
~ You messed up/played with the pitches.
~ It's a glitch.
Not sure what exactly to do. Try to contact the company who made it.