Update at 6:15 a.m. PT Friday: Bitcoin's tumble continued after trading resumed. As of now, the digital currency is trading at $69.
Less than two hours after the resumption of Bitcoin trades following a lengthy suspension, currency exchange Mt. Gox is offline, the apparent victim of a distributed-denial-of-service attack.
"We are experiencing a stronger than usual DDoS," the Tokyo-based exchange said tonight in a Google+ post. "We are working in it."