Microsoft doesn't support codecs like DivX and more. Here's the two web sites you need to know about.
1. http://www.nwlink.com/~zachd/pss/pss.html
2. http://www.moviecodec.com
In closing, your post neglected to share an URL of an example file for others to look over. Also, firewalls have been known to kill off playback.
Bob
First the specifics on my computer:
Model: Gateway 500SE
Intel Pentium 4, 1600 MHz, 100MHz external bus
Memory: 768MB physical
Windows XP SP1 (Windows XP 5.1.2600 Service Pack 1)
Intel Intel PRO/100 VE Network Connection, Cable Modem
I've tried many times over the past few months to get these files to play on my computer, and they will not do so, no matter which program with which I associate them. If I uninstall and then re-install Windows Media Player (most current version)it will play them, though only for a very brief while. I can play a few files, then it will stop playing them (this is without restarting the computer). I get the following message:
"Windows Media Player cannot play the file. The file is either corrupt or the Player does not support the format you are trying to play."
And this is the message error number and related info:
0xC00D1199: Cannot play the file
"Windows Media Player cannot play the file. You may encounter this error message for one of the following reasons:
--The file type is not supported by the Player. The following table lists the file types supported by the Player. If the file type you are trying to play is included in this table, then the file may have been encoded by using a codec that is not supported by Windows Media Player. If this is the case, Windows Media Player cannot play the file.
--The file type is supported by the Player, but the file was compressed by using a codec that is not supported by the Player.
--The file type is supported, but you are trying to play it in a way that is not supported by the Player. For example, you may have attempted to drag a DVD file with a .vob extension from a DVD to the Windows Media Player icon. Or you may have attempted to open a .vob file by clicking Open on the File menu.
--You are trying to play one part of a multipart file. Use a newsreader or other program to combine the files, and then try again."
I've followed up on Microsoft's web page and none of the patches work. Any suggestions?

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic