general problems of the 2007 Lexus GS350

I have a problem with a head light going out intermittently, and occasionally both bulbs and what appears to be the back bulbs too go out leaving my car completely dark, interior lights are sometimes included. A quick off/on of the light switch and the lights are back to normal. I will intermittently turn my lights off then back on so I can control the darkness. I love my Lexus, but feel very unsafe in it, as the lights could go dark and I can't respond quick enough or oncoming traffic will not see me around a curve. I took the car in a couple of years ago to my Lexus dealer, tom williams, and they told me the car battery was weak and causing the problem, shortly thereafter I did replace the battery, but that did not solve the problem. When I bring it to Lexus, they only test it during the day. Still don't know what the problem is. I recently had the car in for the fuel system recall and they rechecked and said again they could not reproduce the problem, I felt like they were telling me I was lying. The most recent incident occurred with 102,000 miles on it, but it has been happening for several years since about 60,000 miles.