strange problem with b-frames off

[dread]

Every my movie encoded with divx 5.01 pro + b-frames off is choppy.
After every keyframe video stops for a sec, and it looks horrible :/
I thought that it was an interleaving problem but I enabled/disabled some options and with b-frames on video is smooth.
Could someone explain me that ? Is there any solution ? Of course besides encoding all my movies with b-frames on ;)

[dragoman]

Hi,

What other options do you have enabled? Perhaps one of the other features (GMC, Q-pel) produces artifacts when you turn b-frames off.

dragoman

[dread]

All other options are disabled.
I've installed ffdshow and... everything is ok :)
So probably problem is on a divx side, not mine...