Need to keep clicking back into rhino

vray
unhandled

#1

dear all,
since loading v-ray for rhino 3 I have had the strange situation where I am modelling away happily and then the cursor leaves rhino and I need to keep clicking back into the rhino viewport to keep modelling- when I unload vray and restart rhino its fine but when both are operation this keeps happenning- after a few minutes anyway…
any ideas, it is extremely annoying…

thanks

jules