i'm john donvan for "nightline" in washington, d.c. >> glaring example of a system on the brink.anks to the firefighters of engine ten and to john donvan. >>> and when we come back, 30 years of "nightline" in three minutes. we say happy birthday to minutes. we say happy birthday to ourselves. this is a history of over 50,0. this is the world record for longevity... and one of the most technologically advanced automobiles on the planet. this is the 9th generation e-class. this is mercedes-benz. see your authorized mercedes-benz dealer for exceptional offers through mercedes-benz financial. ♪ uh... yeah? you gonna ask him this time? about what? our erectile dysfunction. shh...no...i don't want to talk about it. look, you're not alone, millions of men with ed have talked to their doctors. i don't know... we can do this. okay... (announcer) talking to your doctor about ed may be the last thing you want to do, but it's definitely a conversation worth having. twenty million men have had their viagra talk. when you're ready for yours... you'll find helpful tips on talking to your doctor