Without any info on the layers, effects used and so on nobody can tell you much. This error typically pops up when you use an invalid combination of layer switches that collide with an effect's internal logic like using the 3D switch on effects that have their own 3D stuff, but need to be applied to 2D layers... Really impossible to say. You have to be much more specific.
Oh im sorry about that, this happens when I add RSMB to my clips (I use an adjustment layer above the clip and add RSMB to it). After removing RSMB everything works fine but I really want to add RSMB to the clips because it makes them look a lot nicer.
I assume that RSMB is RE: Vision FX Real Smart Motion Blur.
If you have a bunch of layers that need this effect the best workflow is to Pre-compose the layers and then add RSMB. That is the case with all of the RE: Vision FX tools that use motion vector calculations. Unfortunately, I could not find any decent RSMB tutorials on the web, but I do have a lot of experience working with their effects packages and I would not recommend using any of them in an Adjustment layer.
What Rick said. RSMB expects the buffer dimensions to be consistent across time or else its internal math goes crazy. Pre-composing would be way to go.
Thank you very much