Ah ... but you are missing the amazing wonder of inflation. A 42% note can easily be paid if you initiate runaway inflation. If you have inflation of 100% over a year, 42% inflation means that 1 year from now you owe money with 71% of the buying power of those dollars today. Since inflation is across the board, it is usually associated with devaluation of the currency, but in Greece, the currency is the Euro. The other countries realize this, and so they desperatly want to decouple Greece from the Euro, but cannot. Therefore, the only real solution for them is to prop up the Greek economy. The Greeks, knowing this, are reluctant to make any real changes to reduce thier government debt, so you have a standoff.
The article mentions the end of the Euro as one likely way out, and this is why. Buying Greek bonds at 42% is a great deal as long as Greece is part of the Euro. The second they are not ... sell sell sell.