Access violation in AviStreamWrite using Xvid with width>720

I'm writing videos using avifil32.dll, feeding a stream of bitmaps to a 
compressed AVI-stream using AVIStreamWrite. It works fine with the 
latest Xvid-Codec 1.1.3, but only up to a video-width of 720. Beyond 
this, I get an Access-Violation the first time I'm using 
AVIStreamWrite. The same works fine with the Microsoft MP42 codec with 
resolutions up to 1280x960, so it looks like an Xvid-problem from here, 
or what could I have been doing wrong? 

Thanks, 
Renate Schaaf