oh, and to adress Litcube's original problem.
Try this for the start of your vehicle construction queue:
AI State := Exploration
Num Queue Entries := ...
Entry 1 Type := Colonizer
Entry 1 Planet Per Item := 0
Entry 1 Must Have At Least := 2
Entry 2 Type := Attack Base
Entry 2 Planet Per Item := 0
Entry 2 Must Have At Least := 1
Entry 3 Type := ...
Since the AI will put 3 items in the queue, you'll get two colonizers and a scout.
Also make sure that you have a valid 'Attack Base' design from game start (Size Minimum Tonnage := 10) and put some extra supply on it for better exploring

.
Here is an example of a pretty straight-forward one:
Name := Scout
Design Type := Attack Base
Vehicle Type := Ship
Default Strategy := Optimal Firing Range
Size Minimum Tonnage := 10
Size Maximum Tonnage := 400
Num Must Have At Least 1 Ability := 0
Must Have Ability 1 := Weapon
Minimum Speed := 4
Desired Speed := 6
Majority Weapon Family Pick 1 := 22
Majority Weapon Family Pick 2 := 25
Majority Weapon Family Pick 3 := 0
Majority Weapon Family Pick 4 := 0
Majority Weapon Family Pick 5 := 0
Secondary Weapon Family Pick 1 := 25
Secondary Weapon Family Pick 2 := 0
Secondary Weapon Family Pick 3 := 0
Secondary Weapon Family Pick 4 := 0
Secondary Weapon Family Pick 5 := 0
Shields Spaces Per One := 250
Armor Spaces Per One := 0
Majority Comp Spaces Per One := 10000
Majority Comp Ability := Weapon
Secondary Comp Spaces Per One := 200
Secondary Comp Ability := Weapon
Num Misc Abilities := 9
Misc Ability 1 Name := Combat To Hit Offense Plus
Misc Ability 1 Spaces Per One := 10000
Misc Ability 2 Name := Combat To Hit Defense Plus
Misc Ability 2 Spaces Per One := 10000
Misc Ability 3 Name := Supply Storage
Misc Ability 3 Spaces Per One := 10000
Misc Ability 4 Name := Point-Defense
Misc Ability 4 Spaces Per One := 130
Misc Ability 5 Name := Solar Supply Generation
Misc Ability 5 Spaces Per One := 10000
Misc Ability 6 Name := Solar Supply Generation
Misc Ability 6 Spaces Per One := 10000
Misc Ability 7 Name := Extra Movement Generation
Misc Ability 7 Spaces Per One := 10000
Misc Ability 8 Name := Supply Storage
Misc Ability 8 Spaces Per One := 20
Misc Ability 9 Name := Self-Destruct
Misc Ability 9 Spaces Per One := 10000