I think thats normal u shouldnt have a bug i dont think
But i had mission to destroy base of them.
I destroyed it no enemies there , my mates came but only if i leave the area of that base they spawn again ...
Tested when i am in that base 1 hour almost they don't spawn , when i leave it for 2 minuts they spawn.
Searched in google but don't found anything.
Edit:
Here some screens.
Link
Link
Link
[Edited by Arhey, 9/18/2008 10:59:11 AM]