Problem lighting scene with AO in 2.5 *solved*

PROBLEM FIXED

For my animation I have created a factory/warehouse in Blender 2.5. The scene contains 1024 Fluorescent lights. To light the scene, I was originally going to have 1024 area lights. However, after doing a quick test I realized how slow that would be if all of them were casting ray traced shadows. So I began looking at the AO options to light my scene.

All was going well until I added my walls. Suddenly I have these huge artifacts showing up on one of the walls, and I have no idea why. The surface normal is pointing in the right direction and it is exactly the same as the other walls. Increasing the AO samples does not remove the problem.

Would someone please be able to look at my scene and find a solution to my problem?

Thank you in advance.

Please tell me how you solved that problem. Because I heve the same!