On Sunday morning, while China was taking a weekend breather from the financial fireworks caused by the government's weeklong self-inflicted cash and credit crunch, customers of the Industrial and Commercial Bank of China, the world's largest bank, woke to an unpleasant surprise: Their deposits were not available for withdrawal by ATM or teller (online or in-person).

The social-media reaction was swift, filled with exclamation points and lacking in confidence for ICBC, or the Chinese banking system as a whole. "I was just at ICBC to make a withdrawal and was told the system was undergoing an upgrade and withdrawals are temporarily unavailable," tweeted a user in Shenyang on Sina Weibo, China's leading social-media platform. "I called the service hot line, finally someone answered and said they don't know the answer!!!!!!! ICBC: When can we withdraw money? Who can give a clear answer??????????????"

Sunday's outage appears to have started at about 10:30 a.m., and by 11 a.m. there were photos on Sina Weibo of stymied bank customers left mulling in shut-down bank lobbies. "ICBC is closed, the ATM isn't working," tweeted a Sina Weibo user in Xi'an in the midst of the outage. "ICBC says there's a system problem, and my father says the financial crisis has arrived."

Panicked tweets would have been understandable even without the cash crunch. The Chinese have the world's highest personal savings rate, and for lack of better investment options, much of those savings flow into state-owned bank accounts and investment products.

But the week had also been filled with news that China's banks were scrambling to borrow from one another because the central bank was no longer willing to issue easy credit. Days earlier "Shibor" — the English acronym for the Shanghai Interbank Offer Rate, the interest rate charged by banks in loans to each other — trended on Sina Weibo's (normally celebrity-news laden) hot topic list, its surge in popularity running parallel with the government's roll-up of credit to the banks. By lunchtime Sunday, ICBC was in the top 10 on the trending topic list and remained in the top 20 until midday Monday.

The general chain of thought that emerged online seemed logical: If the central bank wouldn't lend money to the banks, and the banks lacked money to lend to one another, then perhaps there wasn't any money around that the banks could give to those trying to withdraw funds.

The explanation that ICBC's customer-service agents gave was the same one the bank tweeted to its Sina Weibo account and later gave the news media: The outage had been caused by a computer upgrade issue, not a cash shortage. The answer is credible insofar as there's no evidence to the contrary.

Still, on China's microblogs and in Communist Party-owned media, there were notes of skepticism. These grew more intense Monday, when news broke that the state-owned Bank of China, China's third-largest bank, suffered an outage that prevented some money transfers. The 21st Century Business Herald newspaper ran an article speculating on connections between the ICBC and Bank of China outages. More than a few microbloggers panicked. Huang Sheng, a professional investor and author with more than 700,000 followers on Sina Weibo, stepped into microblogged conspiracy-mongering: "This is absolutely not caused by system upgrades, because these large banks wouldn't be updating their systems at the same time."

One of the most striking characteristics of the Chinese response to the ICBC outage (the Bank of China outage received far less attention) is the sense that even if the bank is solvent, it must be either incompetent or hiding something. Hua Chige, writing for the Beijing Times, didn't question the ICBC's soundness but still didn't look at its management favorably: "There's a company that can't provide service to customers because of system problems. That's normal and doesn't matter. But what if that company is a Fortune 500 company? That's not normal." Hua may overestimate the value and credibility of Fortune 500 companies, but his contempt for the bank's competence is very much of the Chinese mainstream.

Indeed, among the most popular online memes to emerge from the credit crunch is a group of disparaging Chinese phrases attached to the English-language acronyms for China's biggest state-owned banks. Although they'd circulated before the current crunch, recent events have given them a level of popularity they hadn't previously enjoyed. For example, ICBC has earned the Chinese phrase "ai cun bu cun," which translates, roughly, as the indifferent "It's up to you whether or not to deposit money," and Bank of China earns the concise "bu cun," which translates into "Don't deposit money." There are others, some of which are obscene, and none of which is likely to be embraced by a bank marketing department.

The lack of credibility that China's state-owned banks have with the Chinese public has everything to do with their interconnectedness with the Communist Party and what is often perceived to be their self-serving agenda and self-acknowledged corruption. That's a point that was made, in a brief Monday dialogue on Sina Weibo, started by Wang Mudi, a well-known financial news talking head and producer. "The banks made so much money and yet they have a 'cash shortage,'" he tweeted. "What's the most likely reason?"

Kuo Cheng, a popular writer, blogger and microblogger (with 1.2 million followers), offered five possible locations for the missing money: "A. Under a corrupt officials' bed. B. In a mistress' wallet. C. In a foreign bank account. D. In a bottle of wine in the middle of a state-owned company's table. E. In the pockets of the working people."

It's a potent verdict that should remind China's banking regulators that their biggest problem isn't bringing law and order to the financial industry, but rather who owns that industry in the first place.