The Bitcoin community faced another crisis on Sunday afternoon as the price of the currency on the most popular exchange, Mt.Gox, fell from $17 to pennies in a matter of minutes. Trading was quickly suspended and visitors to the home page were redirected to a statement blaming the crash on a compromised user account. Mt.Gox's Mark Karpeles said that the exchange would be taken offline to give administrators time to roll back the suspect transactions.

The extent of the compromise became clear when a copy of Mt.Gox's user database began circulating online. The file included username, email addres, and hashed password for thousands of Mt.Gox users. Karpeles's statement was updated to acknowledge the breach. He warned users who have re-used the Mt.Gox passwords on other sites to change them.

The crash appears to be the fault of the Mt.Gox exchange rather than a collapse in the value of the currency itself, as the integrity of Bitcoin's underlying peer-to-peer transaction clearing process does not appear to have been compromised. Prices at a competing exchange showed Bitcoins trading down about 25 percent to $13 per Bitcoin earlier today, although it has edged up since.

It's been a bad weekend for Mt.Gox, which until now has been the most popular method for converting between Bitcoins and more conventional currencies. Earlier in the weekend, it was reported that the site was vulnerable to a cross-site request forgery in which a logged-in user could be tricked into submitting fraudulent transaction requests. On Sunday, dozens of irate Bitcoin users pledged to stop using the exchange, arguing that the site's administrators lacked the technical sophistication to build a secure and reliable currency exchange.

But Bitcoin users have few alternatives if they wish to convert their Bitcoins into more stable commodities. A recently-launched competitor, called TradeHill, has capitalized on Mt.Gox's troubles by encouraging members of the Bitcoin community to use their exchange instead. But the site is so new that no one knows if its administrators have the resources or technical expertise to avoid the security and reliability problems that have plagued Mt.Gox.

It's been a wild couple of months for Bitcoin traders. Between April and June, the currency rose from a dollar to more than $30. This month, it fell back to $10 and rose again to $20. It was at $17 at the beginning of this weekend before a string of bad news pushed it down again.

Theoretically, this weekend's developments shouldn't damage Bitcoin's long-term value, since the security model of the underlying currency remains uncompromised. But Bitcoin is a fiat currency; its value ultimately depends on nothing more than public confidence. If the recent string of Bitcoin-related security woes convinces more Bitcoin users to cash out, the currency's value could continue to fall.