Audio Dropout on Transport in Sonar X2 Producer

Hi Ive updated my system with a new laptop (core i7 processor, 8gb ram, ssd). I upgraded to X2 so I now have a 'clean' installation. Ive migrated all my vsts to the new laptop with all programs running from the SSD and samples on the hard drive.
 
Im on a track with about 20 vsts loaded... the cpu usage is minimal... but always now in transport the audio becomes distorted (and sounds like the track has been halved in speed/bpm. Its a pain...
 
I did have similar issues in older version of Sonar but cannot recall what it was that I did to try and resolve this..
 
Any ideas would be appreciated
 
Thanks
Martin