There is a bug in the game which allows you to take over control of an enemy unit by selecting a unit, deselecting it, then hitting the "Back to Unit List" button in the bottom right corner of the screen.
Stephane, lead programmer for HW2 at Relic, on his own time and using the RDN toolkit cooked up this workaround. He has given me the NoBackUI.big file, and instructions for its use...
Download it and save it into the data folder (with the other big files).
Then, create a new shortcut on your desktop for Homeworld 2.... it's path should look something like this.
"c:\program files\sierra\homeworld 2 bin\release\homeworld2.exe" -mod "NoBackUI.big"
What that will do is force the loading of the NoBackUI.big file... what this file does is remove the back button from your screen, so it can't be clicked. To have this work in MP, all users will have to have it installed. Users shouldn't be able to join a game hosted by someone with a NoBackUI mod running if they don't have it running themselves.
As you can see, this is a bandaid fix for the problem. Stephane did it on his own time, using the RDN toolkit. Look for the problem to be a code fix whenever a patch comes out.