Software Version is 188.8.131.52 and all our AP are Cisco Aironet 3600
First, for stability purposes, upgrade to 7.4.121.X. Next, you are using 3600 which supports CleanAir. Enable CleanAir and Persistence Device.
When the the system hears the microwave oven, the WLC will change the power and the channel to the APs most vulnerable to the microwave oven. Your scenario about the microwave oven is THE selling point for Cisco about CleanAir.
Just to add, microwave can affect the whole 2.4ghz spectrum or only a few on the higher channels. If you have CleanAir, you can enable Persistent Devices. This helps when interferes are hear time and time again.