Distortion in GB 10

Upgraded to Yosemite about 3 weeks ago, pretty much nothing but problems - take a look at my history - but we'll leave that out for now.

New version of Garageband 10.

Recorded whole song, guitars, bass, keyboards, vocals - about 4 hours work.

Suddenly, one of the tracks has crackling on it - like electrical.

I lower volume, try everything I can think of, but it's there.

Then it appears on another track.

I quit the song, consider it ruined, go back to Garageband 6.0.5, use that awhile.

Now, three weeks later, decide I'd like to try GB 10 again.

Spend about 4 hours recording a song. Piano, guitar, 4 vocals, easy.

Presently the piano track has crackling on it.

I try to find the source of the crackling.

I don't.

I use REPAIR DISC, restart computer. (Disks are all fine.)

Crackling still there.

And then it gets louder and louder.

I give up, shut Garageband.

This Yosemite is worse that a car someone sells you with nothing but problems.

I want my sunny Sunday back.

There are so many things I could have done rather than sitting in front of a computer recording a song that ends up being ruined.

Or if the crackling had happened during the 4 hours I kept playing the song back, instead of at the end of the recording session.

Really at the end of my rope...really frustrated with Mac, disappointed.