I listened to much of the testimony when it was live on CSPAN. Sebelius did not say it hadn't crashed. She said that there was an outage at the Verizon server that they were depending on.
Whether they should have put America's hopes and dreams in the hands of Verizon, is probably another valid question though.
"For the benefit and enjoyment of the people" -- Inscription, Roosevelt Arch, Northern Gate, Yellowstone, near Gardiner, MT