corrupt data

Howdy folks.  Any thoughts please?
I went open a completed song and was getting errors relating to CakeWalk Sound Center.  I used the sound center on this song to get A: Piano   B: Harpsichord   C:  Strings effect and D:  Female Ahh vocal.
The only thing working is the harpsichord.  The song is playing with awful distortion and a stuttering effect.
I added in the piano effect on a new test track and the piano plays fine when i play the keys on the keybopard.   So i copied the data from the original piano track. Deleted that soft synth and pasted the data to the new piano track.  The distortion is back.   So it looks like the problem is not so much with the  CakeWalk Sound Center but the midi notes within those tracks.  Is it possible for corruption like this to happen and can it be repaired?
It will be a pain to have to re-record those tracks but fortunately the tracks were not very complicated so it wouldn't be the end of the world.  It would be nice though if I could rescue those tracks.  Thanks guys.

Hi Anderton
Good tip and many thanks for that.  Yes it helped with that stuttering for sure.  Sadly, those instruments are still showing a "greyed out" type of icon in the browser.  I wish I knew how to add in a screenshot to show you.  Basically, the Harpsichord add in is showing a normal "illuminated" bright blue icon.  The three faulty ones are kind of dull.  as I say they almost look greyed out. If I delete these and re add them they will work....but of course in doing that I loose the data in those midi tracks.   Oh well.   My own fault.  I had done backups of the song as I went along but forgot to do a backup of the last couple of takes.   Well I guess you learn form these goofs.
Thanks for the help Ander  :) 

hi there Bristol
Thanks for getting back to me.  Yeah, i did actually try drag the data as you suggest and it seems the distortion comes with it. That's why I'm thinking that somehow the actual data has become corrupt.  I wasn't sure if it was possible for that to happen with midi but it really looks like thats what has happened.
  To be honest Bristol..I should have made a backup so my goof :(   

Agentcalm
I wish I knew how to add in a screenshot to show you. 

Go to imgur.com. You upload an image, then it provides a link you can post in the forum. Copy the link that says BBCode and paste it into your post. For example, he's an EQ curve that's using for creating an articulated acoustic guitar sound if it uses a piezo pickup.