floating point exception on decoding

Hi!

I have some avi files with xvid encoded videos which I tried to 
transcode to mpeg2 format. Recently I stumbled upon some avi files 
that give strange errors on decoding. When using ffmpeg for decoding 
I got an error saying: header damaged

When I use xvid (after all the avi header claims to contain video 
encoded with xvid) I get a floating point exception. Well, I took a 
deep breath and started gdb. I was able to trace the bug to the field
DECODER.time_pp which has a value of 0. Now this is not good if you 
want to use this value to divide another number with it (in function 
decoder_bframe in decoder.c line 1326).

Well, I can play the avi with e.g. mplayer or xine. Don't know what 
these programs use to decode the video. But they obiously manage it 
without errors.

So what's going on here? What is this time_pp anyway? Should xvid 
report an error? Should it guess a value if it finds 0 in time_pp?

Martin