As noted above, you've got a carbon MONoxide detector, and it's going off when you run the generator because the generator makes carbon monoxide and it's getting into the rig.
This is the gas that kills people, and generators have become an important source. And if you have any doubt as to its ability to "rise" into the rig, keep in mind that five people died a couple of years ago when their portable's fumes rose into the rig they were sleeping in.
Link.
In that case, the CO detector was disabled...thank your lucky stars that yours is working!
Please don't take any chances- have this thoroughly checked out/repaired before using the genny again.
