Linux/unix server operators need to put this file in the:

half-life/valve/models folder.

Everyone else can delete these files.

I don't have a linux/unix setup and have never seen one.  So...I don't know why this problem occurs, but I hear it is because the Linux server program doesn't come with all the normal game models in it...since most people don't use ventgibs.mdl (they just use regular metal for breaking vents) there usually isn't a problem.

If you still get the error: ventgibs.mdl not found, then you have the .mdl file in the wrong place.  Try talking to some one else who runs a linux server...

Thanks, and enjoy.