Sounds like your computer may be having some problems streaming the video to the Xbox. I tried TVersity and had some issues with this.
I ended up installing uShare on my DLink DNS-323, and I haven't had any problems since (if you have one, or are looking at getting one, check out Fonz's fun_plug, and search for the uShare plugin for that). The only issue with it, is that you have to restart uShare to get it to reindex the files....there may be a way to fix / change this, but I haven't found one yet...it was pretty simple to write a restart command though, that I just have to run whenever I add new files.
Also, I'll note that uShare can be a little finicky, and the configuration file actually has a few mis-named settings (they don't load properly, for example the Xbox setting is supposed to be USHARE_XBOX_STREAMING or something like that, instead of XBOX_STREAMING), so it takes a little tweaking. Once you've got it working though, it's a great program!
If you're running linux on your primary box then you should have no problems getting uShare working on that (I've set it up on my linux server as well).
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