Synchronizing Audio and MIDI

Hello,

I am having a problem with the synchronization of audio and MIDI. Sometimes, not always, I receive this message:

“Error while trying to synchronize Audio and MIDI, Sample Rate 46. ... recognized". 

That value can change. The project’s sample frequency is set at 48 kHz, and I hadn’t any problem till yesterday when I began to record my voice. I have tried to change the MTC and several adjustments but the problem remains. Could you help me?