Qatar recently froze a 5 billion euro investment because it wanted to see if Greece was staying in the euro, George A. Papandreou, Greece’s former prime minister, said in an interview.

Such stalling characterizes the financial decisions of everyone from foreign investors down to families, explained Mr. Papandreou. “Every single household said, ‘Are we going to be in, or not? Should we consume? No, we shouldn’t. Should we borrow? No, let’s take the money out of the banks.’ The banks said, ‘Should we lend? No, we shouldn’t.’ ”

The political upheaval has just deepened the problem.

“We would have had much more growth, much more economic activity, if there was certainty,” he said.

At the port of Piraeus, one of Europe’s largest shipping ports, Nikolas Manesiotis’s 93-year-old spice import business abuts docks where cloves, cinnamon and pepper arrive on ships from India and other faraway lands.

Despite decades-long relationships with his family, suppliers have started demanding cash upfront in lieu of letters of credit for shipments that take three months to arrive. “They say ‘It’s not personal, but our insurance companies will no longer cover business we do with Greek firms,’ ” Mr. Manesiotis said.

That means he must get cash from the Greek businesses he supplies before he can deliver the goods — and many of them have little or no money sitting around. On a recent afternoon, Mr. Manesiotis was preparing to drive around 180 miles to collect money he was owed by a client. “I need to get my cash from him, and if I have to drive four hours to do it, I will,” he said.

Throughout Greece, these problems have turned the basic laws of the market upside down. The economy is suspended by a long chain of arrears.