What's the name of that scenario again? Long time ago I played through most of them and the description sounds familiar; if you give me the name I can check whether I actually played it.
Some of the scenarios require some counter-intuitive tactics (e.g. not expanding in the hope of delaying the Dreadlords attacks, sending waves of small fighters to keep the Dreadlords busy, etc.)
Edit: if you post the name and don't hear back from me 1 week from now, feel free to remind me through a P.M.; sometimes I tend to overlook topics that I've posted in before