Hello,
Currently working with vray 2.30.1 on two huge different scenes.
Ive got 32GB ram availalble and using 13GB while rendering.
On both scenes I am having the same stressful problem which is when i cancel rendering the VFB starts to freak out.
Appears, disappears, doesnt let me close, doesnt let me minimize or sometimes do anything at all.
Remember seing this problem some versions ago but can´t remember if there´s a solution.
Thanks in advance!
Jacinto
Forgot to say I am using Max 2012
This is quite wierd because Ive changed windows user, rendered same scenes and the problem is over.
I had that in 2012, too. It was amazingly annoying, to say the least! There wasn’t a fix, as far as I know. I just used the alt key, until it came back into focus.
I’ve never got that problem and I’m working with 2012.
But I’m with Vray 2.40.03… Did you try it?
I’ve stopped using the vfb entirely because of that.
Wow hope i dont reach that phase.
It´s now working perfectly in another windows user.
Really wierd ****.
Would it be possible to test it with the last official build ?
What about the difference between both windows accounts ? Are they both administrators ?
Yes both are administrators. They are very alike except the desktop picture 
Will try with the latest build as soon as possible but i remember that I had this same problem back in the end of last year with another version.
if its the 2012 its likely because:
1. you have aero enabled in windows
2. you have prograsive refinement enabled in max viewport
Get rid of both and you should be fine
It’ll be the progressive refinement. Once I disabled that, VFB stopped doing its flashy thing.