I have an AP(1131) that keeps disassociating from the controller. It stays alive for about 10 mins then it doens't work anymore. I tired changing the AP but that didn't make a difference. I also tried changing the port on your 500 POE switch. My last effort to fix it was to put the AP on a 3550 switch with a power injector. Still no luck.
I don't understand why its doing this. I am able to connected to it and surf the internet for about 10 mins. After that It leaves the controller and just cycles through different colors.
Some AP's are ok but some other are not, They are same model. We run the code 18.104.22.168 on the WLC's.
Can you try to upgrade your firmware to either 7.0.X or 7.2.X and try?