Vray won't render after rendering a frame

[RALPH_PINEL]

I'm finding that vray sometime won't render after rendering a frame.
I hit the render button but nothing happens.
I have to quite max and rest start again.
rp.

[vlado]

Which 3ds Max and V-Ray version? Also, did you cancel the previous render, or it finished normally?

Best regards,
Vlado

[RALPH_PINEL]

max 2012 vray 2.20.01
I downloaded what i thought was the same version 2.20.02.
It shows that it's 2.20.03 now.
The problem has not happened since.