I dont have the plugins installed that you are using, and currently I am not adding any as I am afraid of my Tizen projects <img src="smileys/smiley1.gif" border="0" align="middle" />
But.. I can offer a comment or two.
1: When you spawn our enemy you just have to exclude the areas you dont want. e.g. if your screensize is 100x100 and you dont want to use the first 10 pixels your random call (if that is what you are using should be: 10+random(80)
2: It sounds like there is a variable you forget to reset when the enemy is killed. Try running it in debug mode and follow the variable that makes your screen flash.