My headlight and inverter box burned out because of condensation built inside the headlamp. I have to replace the whole headlamp assy and the inverter box. Has anybody experienced a similar problem? Do you know what might cause the water inside the headlight?

 

I had this. The water buily up because I had a little leak and water would get in, but not escape. It eventually rusted out my ballast, it was during the winter, and I didn't notice because I didn't drive often.

I simply replaced the ballast and it was as good as new.

But you will want to re-seal your headlights so it doesn't happen again.