Beatscape crashing Sonar 8

I have Sonar 8 PE (8.3.1.372) on Vista  with Novation nio 2/4 audio device.
 
I am adding some loops to a rhythm track using beatscape, and it is a lot of fun.
However,
the project saves fine until I silence a slice in one of my beatscape pads, then when I try to save the project it hangs sonar. The loop is actually a loopmasters loop, not a rex file or a pre-loaded file, but all the transient markers appear in the correct place and it plays in prefect time with the project tempo.
I'm not sure what beatscape version I'm on (not sure where to find it).
Any help is always greatly appreciated.
thanks
Luke