Cathodes burned out after 3 months

i have a set of blue cathodes under the dash of my car, i've had them in there for about 3 months. tonight i suddenly smelled an electrical burning smell and i noticed one of the cathode tubes was only half lit.  i discovered that the smell was coming from the power converter box, whatever its called.  i also noticed in the cathode tubes were kinda burning at the ends, glowing orange and burning away the plastic.  obviously it's because of the power converter box burning out.  so what may have caused this?  they've been installed for 3 months and i've had no previous problems.  anything i should consider before buying a new set?