I think this

http://www.computerworld.com/s/article/9237979/Bitcoin_exchange_faces_DDoS_even_as_the_digital_currency_surges?source=rss_news_analysis&utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+computerworld%2Fs%2Ffeed%2Ftype%2Fnewsanalysis+%28Computerworld+News+Analysis%29

might be responsible for the failed Mt.Gox orders last night. Mt.Gox was under a DDOS attack which caused the price to drop form $95-$70. So I would suspect that bitinstant is not to blame for last night.