I reinstalled Divx 5. Files that are encoded with it play, but I can't use Virtaul Dub, TMPGEnc or Adobe Premiere to convert them. Virtaul Dub gives and error, and TMPGEnc and Adobe Premiere gets a black screen. I reinstalled it many times. Anyone can help.

Virtual dub 1.4.9
Divx 5.0

VirtaulDub requires a Video for windows (VFW) compatible codec to decompress video.

DirectShow codecs, such as those used by Windows Media Player, are not suitable

PRO, standard or GAIN version??

Try installing the newest version (5.01) at www.divx.com
This happened to me too, seems like stuff encoded with 5.01 isn't compatible with the 5.0 codec.