Voice Recording - M250

Hi all,
My sansa m250 is firmware version 2.2.5 and i’ve tried everething to fix this problem. When I hear the voice recording, the sound recorded apresents I kind of little cuts, and the same file sometimes, the sound was acelerate. I test the voice recording in front of my FM stereo, then after I will hear the sound recorded and I hear that. 
To tried fix this problem i’ve formated the sansa and formated my desktop.
Sorry for any errors in my writing.

Thanks for your attencion