Anybody using Ground Combat/Units??

[General Hawkwing]

One experience I had with ground combat went as follows:
I had defeated the planet's space station and had destroyed the 3 weapon platforms. (The planet's cargo showed 0 platforms.)I then brought my troop ship in and dropped them to capture the planet. When it went to the ground combat screen, the planet defenses showed the weapon platforms (still at 0) and ZAP one combat tick and all my troops were gone.
I would think that destroyed platforms whould not have counted in the combat. Is this a bug?
Please note that this all occurred within one 30 turn combat.
BTW I then used my attack ships to wipe the planet clean, that'll show 'em.