Hi Marcio, welcome to the board! My guess is that your amp is too underpowered for your cab. The specs on the Crown XLS 202 are 200 watts per channel at 8 ohms, 300 watts per channel at 4 ohms, 400 watts at 8 ohms bridged. Generally you want an amp that matches up to or exceeds the requirements of your cabs. You didn't state whether your cab is a 4 ohm or 8 ohm cab, which is an important consideration in determining how much amp you need.
My rig is powered by a QSC PLX 2402. Crown makes very good quality amps, but my guess is that if your amp is going into protection mode then it's probably too underpowered for your cab. If your cab is a 4 ohm cab, then you need something that will provide at least 600 watts continuous into 4 ohms.
There are other factors to consider as well; but based on what you've told us, that's a good starting point.