Sonar X3 Studio - Pops and Stutters

Hi,
 
I am working on my first Sonar X3 Studio project.  Relatively speaking, it is a simple production.  Prior to owning X3, I created a song in Garage Band using my iPad.  I exported this tune as an audio file, which I've inserted in X3 Studio.  I've been working on vocals for over a week, no problems.  Tonight, I am wrapping up my two tracks of vocals.  But now my production is popping and stuttering.  It's unlistenable its so bad.  My computer is a power house, it can't be that [Win 7 Pro, 64 bit, Intel Core i7 CPU, 3.40 ghz, 16 gb ram].  I do know that I changed some buffer settings when I tried to use Melodyne.  Under sync and cashing, My Playback and Record I/O buffer is 256.  It was 1024, both settings didn't stop this.  Also, enabled read and write caching are off (tried both off and on, no good).
 
I've had productions with lesser computing power and many more tracks with older software (MC6, MC5, Home Studio 9) with no problems.  Can anybody help me, this is very frustrating....and since it wasn't happening the other 6 sessions working on this song, I am really stumped.
 
BTW, the only affects I'm using are Compressor on each of two vocal tracks and reverb on each of two vocal tracks.
 
Thanks in advance for your help.
 
Patrick