XviD not MPEG4 compatible?

[Boardlord]

Sorry if this was asked or discussed before, but I haven't found anything about this matter.
I encoded a short clip with Divx5 and XviD. Followed everything on Doom9's guide, the .mp4 file from the Divx5 video played fine with WMP4Player, but the one from the XviD video crashed the player. Anyone knows why?
Thanks in advance

[Doom9]

would you consider DivXNetwork more likely to create a specs compliant software than an actual open source project (which is considered by many to be the reference implementation)? Did I not write that I created my testfiles with xvid and that divx5 wouldn't work (most likely b-frame related)..

[Prosper]

No, I get the same results as boardlord. I just assume its due to the alpha nature of xvid, and I'll try it again with a later build sometime.